SECTION 100
Pesticide Analytical Manual Vol. I
300–1
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
Table of Contents
page date
301: Multiclass MRMs: Concept and Application
301 A: Recommended Application of Multiclass MRMs 301-1 1/94
301 B: Capabilities and Limitations of MRMs 301-4 1/94
Influence of Solvents on Methodology 301-4 1/94
Extraction 301-4 1/94
Cleanup 301-6 1/94
Determinative Steps 301-7 1/94
References 301-7 1/94
302: Method I for Nonfatty Foods
Basic References 302-1 1/94
General Principles 302-1 1/94
Applicability 302-1 1/94
Method Modules 302-1 1/94
Validation 302-5 1/94
Chapter 1
Regulatory Operations
Chapter 2
General Analytical
Operations and Information
Chapter 3
Multiclass
MRMs
Chapter 5
GLC
Chapter 4
Selective
MRMs
Chapter 6
HPLC
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
300–2
SECTION 100 Pesticide Analytical Manual Vol. I
E1 Extraction with acetone, liquid-liquid
partitioning with petroleum ether/
methylene chloride 302-7 1/94
E2 Extraction with acetone, removal of water
with 40 g Hydromatrix 302-9 1/94
E3 Extraction with acetone, removal of water
with 25 g Hydromatrix 302-12 1/94
E4 Extraction with water/acetone, liquid-liquid
partitioning with petroleum ether/
methylene chloride 302-13 1/94
E5 Extraction with acetone, liquid-liquid
partitioning with acetone/methylene
chloride 302-15 10/99
E6 Extraction with water/acetone, liquid-liquid
partitioning with acetone/methylene
chloride 302-15 10/99
E7 Extraction with acetone and solid phase
extraction cartridges, liquid-liquid
partitioning 302-17 10/99
C1 Florisil column (4 g) cleanup, with one
methylene chloride eluant 302-19 1/94
C2 Charcoal/Celite/magnesium oxide column
cleanup 302-21 1/94
C3 Charcoal/Silanized Celite column cleanup 302-23 1/94
C4 C-18 cartridge cleanup 302-25 1/94
C5 Florisil column cleanup, with mixed ether
eluants 302-27 1/94
C6 SAX/PSA cartridge cleanup 302-29 10/99
Determination 302-31 10/97
Confirmation 302-32 1/94
DG1 GLC, 100% methyl siloxane, 200 C, EC 302-33 1/94
DG2 GLC, 100% methyl siloxane, 200 C, FPD-P 302-35 10/97
DG3 GLC, 100% methyl siloxane, 200 C, ELCD-X 302-37 1/94
DG4 GLC, 100% methyl siloxane, 200 C, ELCD-N 302-39 1/94
DG5 GLC, 100% methyl siloxane, 200 ? C, N/P 302-41 10/97
DG6 GLC, 100% methyl siloxane, 130 C, FID 302-43 1/94
DG7 GLC, 100% methyl siloxane, 130 C, EC 302-45 1/94
DG8 GLC, 100% methyl siloxane, 130 C, FPD-P 302-47 1/94
DG9 GLC, 100% methyl siloxane, 130 C, ELCD-X 302-49 1/94
DG10 GLC, 100% methyl siloxane, 230 C, EC 302-51 1/94
DG11 GLC, 100% methyl siloxane, 230 C, FPD-P 302-53 1/94
DG12 GLC, 100% methyl siloxane, 230 C, ELCD-X 302-55 1/94
DG13 GLC, 50% phenyl, 50% methyl siloxane,
200 C, EC 302-57 1/94
page date
SECTION 100
Pesticide Analytical Manual Vol. I
300–3
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
DG14 GLC, 50% phenyl, 50% methyl siloxane,
200 C, FPD-P 302-59 10/97
DG15 GLC, 50% phenyl, 50% methyl siloxane,
230 C, FPD-S 302-61 1/94
DG16 GLC, 50% phenyl, 50% methyl siloxane,
200 C, ELCD-X 302-63 1/94
DG17 GLC, 50% phenyl, 50% methyl siloxane,
200 C, N/P 302-65 10/97
DG18 GLC, 50% cyanopropylphenyl, 50% methyl
siloxane, 200 C, EC 302-67 1/94
DG19 GLC, 50% cyanopropylphenyl, 50% methyl
siloxane, 200 C, FPD-P 302-69 1/94
303: Method II for Nonfatty Foods
Basic References 303-1 1/94
General Principles 303-1 1/94
Applicability 303-1 1/94
Method Modules 303-1 1/94
Validation 303-3 1/94
E1 Extraction with acetonitrile, partition into
petroleum ether 303-7 1/94
E2 Extraction from eggs with acetonitrile,
partition into petroleum ether 303-8 1/94
E3 Extraction with 35% water/acetonitrile,
partition into petroleum ether 303-9 1/94
E4 Extraction with acetonitrile and water,
partition into petroleum ether 303-9 1/94
E5 Extraction with heated acetonitrile and
water, partition into petroleum ether 303-10 1/94
C1 Florisil column cleanup, with three ethyl
ether/petroleum ether eluants 303-11 1/94
C2 Florisil column cleanup, with three
methylene chloride eluants 303-12 1/94
Determination 303-13 1/94
Confirmation 303-13 1/94
304: Method for Fatty Foods
Basic Reference 304-1 1/94
General Principles 304-1 1/94
Applicability 304-1 1/94
Method Modules 304-1 1/94
Validation 304-3 1/94
E1 Extraction of fat with sodium sulfate,
petroleum ether 304-5 1/94
E2 Small scale extraction of fat with sodium
sulfate, petroleum ether 304-7 1/94
page date
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
300–4
SECTION 100 Pesticide Analytical Manual Vol. I
E3 Extraction of fat by filtering 304-9 1/94
E4 Extraction of fat with solvents from
denatured product 304-11 1/94
E5 Extraction of fat with solvents 304-13 1/94
C1 Acetonitrile-petroleum ether partitioning,
Florisil column cleanup, three mixed
ether eluants 304-15 1/94
C2 Acetonitrile-petroleum ether partitioning,
Florisil column cleanup, three methylene
chloride eluants 304-18 1/94
C3 Acetonitrile-petroleum ether partitioning,
Florisil column cleanup, petroleum ether
and three mixed ether eluants 304-19 1/94
C4 Acetonitrile-petroleum ether partitioning,
Florisil column cleanup, petroleum ether
and three methylene chloride eluants 304-19 1/94
C5 Gel permeation chromatography (GPC) 304-21 1/94
C6 GPC, Florisil column (4 g) cleanup, three
methylene chloride eluants 304-24 1/94
C7 Florisil column (4 g) cleanup, two mixed
ether eluants, optional alkaline hydrolysis 304-27 1/94
C8 Dispersion on alumina, Florisil column
cleanup, three mixed ether eluants 304-29 1/94
C9 Dispersion on alumina, Florisil column
cleanup, three methylene chloride eluants 304-32 1/94
Determination 304-33 1/94
Confirmation 304-33 1/94
Figures
301-a Recommended Approach to Analysis of Foods 301-2 1/94
302 Recommended Approach: Nonfatty Foods 302-4 10/99
303-a Recommended Approach: Nonfatty Foods 303-3 1/94
304-a Recommended Approach: Fatty Foods 304-3 1/94
304-b Delivery Tube Apparatus 304-12 1/94
Tables
302-a: Recovery of Chemicals Through Method 302
(E1-E3 + DG1-DG19) 302-a-1 9/96
302-b: Recovery of Chemicals Through Method 302
(E1-E3 + C5 + DG1-DG19) 302-b-1 9/96
302-c: Recovery of Chemicals Through Method 302
E1-E3 + C3 + DL1) 302-c-1 9/96
302-d: Recovery of Chemicals Through Method 302
(E2/E3 + C1 + DG1-DG19) 302-d-1 9/96
page date
SECTION 100
Pesticide Analytical Manual Vol. I
300–5
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302-e: Recovery of Chemicals Through Method 302
(E1/E4 + C4 + DL1) 302-e-1 9/96
302-f: Recovery of Chemicals Through Method 302
(E7 + C6 + DG1-DG3, DG6-DG7, DG10,
DG13-DG14, or DG16) 302-f-1 10/99
303-a: Recovery of Chemicals Through Method 303
(E1-E5 + C1 or C2 + DG1-DG19) 303-a-1 9/96
304-a: Recovery of Chemicals Through Method 304
(E1-E5 + C1-C4 + DG1-DG19) 304-a-1 9/96
304-b: Recovery of Chemicals Through Method 304
(E1-E5 + C6 + DG1-DG19) 304-b-1 9/96
304-c: Recovery of Chemicals Through Method 304
(E2 + C7 + DG1-DG19) 304-c-1 9/96
page date
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
300–6
SECTION 100 Pesticide Analytical Manual Vol. I
Pesticide Analytical Manual Vol. I SECTION 301
301–1
Transmittal No. 94-1 (1/94)
Form FDA 2905a (6/92)
301: MULTICLASS MRMS: CONCEPT AND APPLICATION
Pesticide multiresidue methods (MRMs) are capable of simultaneously determin-
ing more than one residue in a single analysis; this multiresidue capability is
provided by a GLC or HPLC determinative step that separates residues from one
another before detection. The MRM concept is raised to a higher dimension when
a single extract is examined with more than one chromatographic determinative
step, each providing coverage of residues in a different class, e.g., chlorinated
hydrocarbons, organophosphates, and carbamates. PAM I refers to these broad
scope methods as “multiclass MRMs.”
A multiclass MRM is potentially capable of determining any residue extracted by
its extraction step; PAM I multiclass MRMs extract residues with organic solvents
known to remove most nonionic residues from food commodities. Each determi-
native step in a multiclass MRM provides coverage for a particular group of resi-
dues in the extract, and each cleanup step is designed to purify the extract suffi-
ciently to permit accurate determination. A multiclass MRM scheme can be ex-
panded continually as new technologies are developed and adapted.
This introductory section presents a recommended approach to application of
multiclass MRMs and background information with which any analyst using such
methods should be familiar.
301 A: RECOMMENDED APPLICATION OF MULTICLASS MRMS
Whenever a sample of unknown pesticide treatment history is analyzed, and no
residue(s) is targeted, a multiclass MRM should be used to provide the broadest
coverage of potential residues; Figure 301-a displays the recommended multiclass
MRM for each commodity category. The more detailed scheme provided with
each method (Figures 302-a, 303-a, 304-a) directs the user to recommended
module(s) for particular commodities. The user may choose as many or as few of
these modules as time and resources permit; once residues are extracted, each
determinative step extends coverage of the analysis to additional compounds.
Follow these directions to maximize coverage of residues without sacrificing quan-
titative accuracy:
? For broadest coverage of potential residues, examine the uncleaned
extract by determinative steps that are sufficiently selective to permit
residue identification and quantitation in the presence of co-extractives.
? Following determination by selective determinative steps, clean up the
extract as needed to permit additional determinations; these may in-
clude determinative steps designed for specific groups of residues (e.g.,
from Chapter 4 methods).
? When a peak appears in the chromatogram of the extract, use the fol-
lowing PAM I tables to tentatively identify the residue and to choose the
additional analyses needed for optimum identification, quantitation, and/
or confirmation:
1) PESTDATA (Appendix I). Compare GLC relative retention time (rrt)
of the residue to lists of rrts on several common GLC columns
301–2
Transmittal No. 94-1 (1/94)
Form FDA 2905a (6/92)
Pesticide Analytical Manual Vol. ISECTION 301
Figure 301-a
Recommended Approach to Analysis of Foods
<2% fat,
>75% water
302
<2% fat,
<75% water
303
>2% fat
304
Appendix I:
PESTDATA
Identify residues
(tentative)
Index:
Methods
Compare methods
Table
30N-n
Review details
Pesticide Analytical Manual Vol. I SECTION 301
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Form FDA 2905a (6/92)
for the first clue to residue identity. Review method behavior infor-
mation for additional clues about which potential candidate(s) be-
haves in the same way as the residue. Inject solutions of appropriate
reference standard(s) for comparison to the residue peak.
If retention times of residue and reference standard match, use
PESTDATA information on the chemical’s molecular formula and
its rrts on other columns as a guide to selecting other determina-
tions that will provide confirmatory evidence. If additional analyses
are needed, choose appropriate other methods from PESTDATA
listings of recoveries, Index to Methods, and tables related to spe-
cific methods, below.
PESTDATA rrts are for GLC systems only. Retention times from the
HPLC determinative steps of Sections 401, 403, and 404 are included
in the tables that accompany those methods. Use those tables to
tentatively identify residues found.
2) Index to Methods. Use this summary as a guide to other method(s)
available for a tentatively identified residue. Review method tables,
below, for additional details.
3) Tables 302, 303, 304, 401, 402, 403, and 404. When a residue is
tentatively identified, review method tables for details about special
situations that may diminish recoveries, opportunities to improve
recoveries, need for particular determinative step(s), etc. Decide what
additional analyses are necessary based on this information.
? When tabulated information about behavior of the tentatively identified
residue indicates that the method used provided only incomplete recov-
ery, re-analyze the commodity with another method capable of complete
recovery of the residue.
(The analyst should be aware that all data in PAM I tables reflect the
best information available but do not guarantee that results will be iden-
tical in every situation. Data have been collected for 30 years from many
sources, including original method development studies, recovery stud-
ies by FDA laboratories, recovery studies by pesticide registrants and/or
their contract laboratories, and collaborative and validation studies con-
ducted under the auspices of AOAC International. Particular results
may represent many analyses or only one, may have been performed
with or without sample present, through complete methods or through
individual procedures of a method, and with or without use of lauric
acid adsorption value for Florisil column weight adjustment.)
? When the method used has not been previously validated for the resi-
due/commodity combination, develop the necessary validation data.
Inherent in this approach to residue analysis is the acknowledgment that no
multiclass MRM is quantitatively valid for all residues it is capable of detecting.
Thus, re-analysis by other method(s) is required when a residue(s) is identified by
a method known to be incapable of confirmatory identification and/or quantita-
tive accuracy. Demonstration of method validity for any residue/commodity com-
bination that is reported is the responsibility of the analyst using the method.
301–4
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Form FDA 2905a (6/92)
Pesticide Analytical Manual Vol. ISECTION 301
301 B: CAPABILITIES AND LIMITATIONS OF MRMS
Several aspects of an MRM influence its scope as a multiclass method: (1) thor-
oughness with which the extraction solvent and physical procedure are capable of
extracting residues from the sample, (2) ability of subsequent cleanup techniques
to remove sample co-extractives without removing residues, and (3) the number of
different determinative steps used to examine the extract. During method devel-
opment, a researcher evaluates each step of a method and makes choices based on
optimum performance. Subsequent interlaboratory validation verifies that the
method produces accurate results when performed as written.
This edition of PAM I presents MRMs as a series of modules, in recognition of
standard practices in laboratories required to analyze many different commodities
for many different potential residues. Modules presented within the same section
in this manual were not necessarily developed at the same time or by the same
researcher. Module combinations that have undergone interlaboratory validation
are listed and recommended, but analysts may find it necessary to combine other
modules to meet a particular need. Any such combination must be supported by
data that validate its use in the situation. Steps of an MRM must be compatible
with one another for the whole method to be applied in a valid manner.
This section provides background information to assist the analyst in making valid
choices and avoiding potential pitfalls. Included here are discussions about the
overall influence solvents have on method performance and important informa-
tion about each category of method modules (extraction, cleanup, and determina-
tive steps). Analysts combining method modules must be aware of the following
concerns and take precautions to ensure that only appropriate combinations are
used.
Influence of Solvents on Methodology
Choice of solvent(s) is among the most important decisions made by a researcher
developing an analytical method. Analysts using these methods must also be aware
of the following considerations related to solvents used in individual modules:
Availability of Pure Solvent. Solvent purity is essential to avoid potential interfer-
ences in the determinative step; impurities are usually concentrated during the
evaporation steps included in most residue methods. Higher purity solvents invari-
ably cost more, and it may be possible to use less expensive, lower purity materials
if a solvent reagent blank examined by appropriate determinative step(s) (Section
204) supports their acceptability.
Detector Response to Solvent. GLC detectors used in residue determinations are
usually selective for an element in the analyte molecule, so the final extract must
not be dissolved in a solvent containing element(s) to which the detector(s) re-
spond. For example, no trace of acetonitrile can be present when a nitrogen-
selective detector is used, and no methylene chloride when a halogen-selective
detector is used. HPLC detectors commonly used in residue determination pre-
clude use of solvents that absorb UV light or fluoresce at the wavelength used
during determination.
Solvents can adversely affect detectors in other ways, such as the deleterious
but poorly defined effect acetonitrile has on electroconductivity detectors.
Pesticide Analytical Manual Vol. I SECTION 301
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Experiences with such effects are usually noted in a method so use of particular
solvents can be avoided.
Polarity. Increasing the polarity of an extraction solvent may improve a method’s
ability to extract particular residues, but it usually also increases the amount of co-
extractives. The presence of polar solvents may also affect subsequent cleanup
steps, so residues may need to be transferred to a different solvent before the next
step of the method is performed.
Boiling Point. Solvents with a low boiling point are preferred, if evaporation to
accommodate detector compatibility or appropriate polarity is necessary. In some
cases, a solvent with a relatively high boiling point can be evaporated at a lower
temperature if an azeotrope is first formed by addition of another solvent. Several
types of evaporation apparatus exist (Section 202 C), and choice of which to use is
often related to the boiling point of a particular solvent.
Toxicity. Solvents vary in toxicity, and laboratories should choose the least toxic
among equivalent choices. Certain solvents (benzene, carbon tetrachloride) should
no longer be used in residue analysis. Concentration and evaporation steps must
be performed in an adequately ventilated hood, and other standard safety precau-
tions must be followed (Section 207).
Extraction
The necessity of using water-miscible solvents to extract pesticide residues from
high moisture products has long been established, as has the necessity of a “blend-
ing type” extraction process [1-4]. Acetone (Section 302), acetonitrile (Section
303), and methanol (Sections 401, 403) are used in PAM I multiclass and selective
MRMs to extract nonionic residues from fruits and vegetables. Variations in polar-
ity may affect the degree to which each can extract any particular residue [5-8].
Because extraction capabilities of these solvents are similar, other characteristics
affect which solvent a developer chooses to use in a method. For example, devel-
opers of the method in Section 302 used acetone as extractant instead of acetoni-
trile (Section 303) because it is less toxic, has a lower boiling point (57 C vs. 82
C), does not affect detectors adversely, and does not form a two-phase system with
water during analysis of fruit, as acetonitrile does [9].
Liquid-liquid partitioning of residues from initial extractant to nonaqueous sol-
vent is a step common to most MRMs. Nature of the solvent(s) used in this step
affects the degree of transfer of both residues and co-extractives. For example, in
Section 302 E1, petroleum ether is included in the separator with aqueous acetone
and methylene chloride to reduce the amount of polar plant constituents that
partition into the organic phase. However, in a method variation targeted at the
highly polar methamidophos, petroleum ether is replaced with acetone to im-
prove partitioning of methamidophos from the aqueous to the organic layer [10].
Any MRM is applied with the understanding that certain residues are particularly
difficult to extract, e.g., the polar residue methamidophos, above. In such cases,
notation of partial recovery is made in the table(s) of data that accompany the
method description. Tentative identification of a residue known to be incom-
pletely extracted by the method in use should then lead to re-analysis by another
method or variation.
301–6
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Pesticide Analytical Manual Vol. ISECTION 301
Certain commodities also present greater challenges to the extraction process, and
methods may include special steps as an accommodation. Dry products are ex-
tracted with combinations of organic solvent and water to make up for the absence
of water in the commodity itself. Several studies support the use of water/acetoni-
trile (Section 303 E3) for this purpose [11-13]. Water/acetone (Section 302 E4) is
also used but has been found in some cases to extract less residue than water/
acetonitrile [14, 15]; the two methods should be used to check one another when
a residue has been identified that can be determined by both methods.
Extraction of residues from fatty products (e.g., Section 304 E1-E5) has tradition-
ally been aimed at nonpolar, lipophilic residues, which are readily extracted from
the product when the fat itself is extracted. Currently, no method is available in
this manual for quantitative determination of polar residues in fatty products.
Some residues absorbed from soil by plants, e.g., dieldrin in potatoes, have been
shown to be incompletely extracted by methods such as Section 303 [13]; other
root-absorbed residues (e.g., dieldrin and DDT in carrots) have been extracted
completely by the same procedure [16, 17]. Laboratories analyzing root crops
must be aware that the method may not be extracting all the residue present.
Other, more exhaustive processes, such as use of a Soxhlet extractor [18], may be
necessary if the residue or commodity warrants.
Cleanup
Cleanup steps are designed to purify extracts to permit more definitive identifica-
tion of residues at lower limits of quantitation, and to minimize adverse effects on
determinative step instrumentation. However, almost all cleanup steps adsorb,
destroy, or otherwise remove at least some residues from the extract. Thus, cleanup
may reduce the number of detectable residues in the final extract.
Schemes for multiclass MRMs attempt to determine as many residues as possible
by examining uncleaned extracts with selective detectors, e.g., flame photometric
and electrolytic conductivity (GLC) and fluorescence (HPLC). Cleanup can subse-
quently be performed on the extract to permit determination with less selective
detectors, e.g., electron capture (GLC) or UV (HPLC). Use of several cleanup
steps, each on a separate aliquot of extract, permits examination of each aliquot
with a different determinative step. This approach provides coverage for the maxi-
mum number of residues, excluding only those not recovered from any cleanup
step and also not determined by initial selective detectors.
Residues can often be detected but not reliably quantitated in an uncleaned ex-
tract; quantitation may be possible once the extract is cleaned up using a tech-
nique known to recover the particular residue. Other residues can be quantita-
tively measured only by re-analysis with a different extraction step. Tables of recov-
ery data for each method provide the analyst with information to guide the choice
of an appropriate cleanup technique or alternative method.
Many cleanup steps involve chromatography of the extract solution on a column
or cartridge. Choices of the column/cartridge material and eluting solvent(s)
dictate what chemicals can be recovered; e.g., columns of the adsorbent Florisil
provide suitable cleanup of relatively nonpolar residues (Sections 302 C1, 303 C1,
etc.). Increasing the polarity of the eluant permits recovery of more polar residues
but decreases the degree of cleanup, because more co-extractives are also eluted.
Pesticide Analytical Manual Vol. I SECTION 301
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Transmittal No. 94-1 (1/94)
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Very polar residues usually cannot be eluted from Florisil no matter how polar an
eluant is used. Instead, charcoal columns are often used for cleaning up extracts
containing polar residues, e.g., Sections 302 C2 and C3.
The nature of the solvent in which the extract is dissolved when placed on a
cleanup column may affect which residues elute from the column. Recovery data
associated with a method are valid only when the extract is in the specified solvent.
When combining method modules, the extract added to a cleanup column may be
in a solvent different from that originally specified; in such cases, recovery data
may not be applicable. To make use of existing tables of data related to chemicals
recovered through a method, it may be necessary to change the extract solvent by
evaporation or azeotroping.
Determinative Steps
Use of minimal cleanup in an MRM reduces analysis time and reagent costs, but it
can jeopardize determinative step reliability by introducing co-extractives that in-
terfere with the determination or cause physical damage to the system. Presence of
materials to which the detector responds can cause (1) false reports of residues
not actually present, (2) inaccurate quantitation of residues, or (3) complete mask-
ing of residues. Risk of chromatographic degradation is increased by repetitive
injection of an uncleaned extract.
The analyst using methods from PAM I is responsible for ensuring that extract
injected into any determinative step system does not contain potential interfer-
ences or materials that adversely affect chromatographic performance. Sections
501 C and 601 E provide recommendations related to determinations with GLC
and HPLC systems, respectively. Analytical accuracy and minimal disruption of
laboratory operations will result if reasonable use of cleanup steps and regular
maintenance of instruments are both employed.
In certain cases, special precautions are needed to detect particular residues. For
example, thiometon is known to break down while standing in the extract solution
of Section 302 E1; examination of the extract soon after its preparation permits
determination of thiometon residues that would not otherwise be detectable. Notes
are included in the method tables of data to provide such advice.
References
[1] Klein, A.K. (1958) J. Assoc. Off. Agric. Chem. 41, 551-555
[2] Klein, A.K., et al. (1959) J. Assoc. Off. Agric. Chem. 42, 539-544
[3] Burke, J.A., and Porter, M.L. (1966) J. Assoc. Off. Anal. Chem. 49, 1157-1162
[4] Porter, M.L., and Burke, J.A. (1968) J. Assoc. Off. Anal. Chem. 51, 63-64
[5] Watts, R.R. (1971) J. Assoc. Off. Anal. Chem. 54, 953-958
[6] Wheeler, W.B., et al. (1978) J. Agric. Food Chem. 26, 1333-1337
[7] Sonobe, H., et al. (1982) J. Agric. Food Chem. 30, 696-702
301–8
Transmittal No. 94-1 (1/94)
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Pesticide Analytical Manual Vol. ISECTION 301
[8] Sonobe, H., et al. (1983) J. Agric. Food Chem. 31, 96-104
[9] Luke, M.A., et al. (1975) J. Assoc. Off. Anal. Chem. 58, 1020-1026
[10] Luke, M.A., and Doose, G.M. (1983) Bull. Environ. Contam. Toxicol. 30, 110-
116
[11] Bertuzzi, P.F., et al. (1967) J. Assoc. Off. Anal. Chem. 50, 623-627
[12] Burke, J.A., and Porter, M.L. (1967) J. Assoc. Off. Anal. Chem. 50, 1260-1262
[13] Burke, J.A., et al. (1971) J. Assoc. Off. Anal. Chem. 54, 142-146
[14] Cox, B., and Uribe, M. (Nov. 1984) “Comparison of Acetone and Acetoni-
trile for Extraction of Endrin from Mung Beans,” LIB 2881, FDA, Rockville,
MD
[15] Weishaar, J.A. (Nov. 1989) “Comparison of Acetone-Water and Acetonitrile-
Water for Extraction of Pirimiphos Methyl from Pasta Products,” LIB 3397,
FDA, Rockville, MD
[16] Porter, M.L., et al. (Dec. 1970) FDA private communication
[17] Luke, M.A. (Feb. 1971) FDA private communication
[18] Mumma, R.O., et al. (1966) Science 152, 530-531
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
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SECTION 302Pesticide Analytical Manual Vol. I
302: METHOD I FOR NONFATTY FOODS
BASIC REFERENCES
Luke, M.A., et al. (1975) J. Assoc. Off. Anal. Chem. 58, 1020-1026
Luke, M.A., et al. (1981) J. Assoc. Off. Anal. Chem. 64, 1187-1195
GENERAL PRINCIPLES
Residues are extracted from nonfatty foods by blending with acetone or water/
acetone, then transferred from the filtered aqueous extract into organic solvent. The
extract is cleaned up if necessary and examined by various determinative steps; the
amount of cleanup necessary is dictated by the determinative step(s) to be used and
by the type of commodity being analyzed.
APPLICABILITY
Consult Guide to PAM I for additional information pertinent to the appropriate
application of multiresidue methodology.
Method is applicable to nonionic residues in nonfatty foods. Cleanup steps may be
needed for particularly dirty extracts or for examination by less selective detectors;
some residues may be lost during cleanup. Extract is amenable to examination by
many determinative steps, and the residues covered by a particular analysis are
dependent on the number of different determinative steps used. See Tables 302-a and
302-b, following the method description, for results of recovery tests.
METHOD MODULES
Choose from these method modules, using Figure 302-a for guidance:
Extraction (E) Recommended Use
E1 (p. 302-7) Extraction with acetone, liquid-liquid nonfatty, high moisture
partitioning with petroleum ether/ commodities
methylene chloride
E2 (p. 302-9) Extraction with acetone, removal of nonfatty, high moisture
water with 40 g Hydromatrix commodities
E3 (p. 302-11) Extraction with acetone, removal of alternative to E2 for
water with 25 g Hydromatrix reduction in solvent use
E4 (p. 302-13) Extraction with water/acetone, nonfatty, low moisture
liquid-liquid partitioning with commodities
petroleum ether/methylene chloride
E5 (p. 302-15) Extraction with acetone, alternative to E1
liquid-liquid partitioning with for relatively polar
acetone/methylene chloride residues
E6 (p. 302-16) Extraction with water/acetone, alternative to E4 for
liquid-liquid partitioning with relatively polar
acetone/methylene chloride residues
E7 (p. 302-17) Extraction with acetone and nonfatty, high moisture
solid phase extraction cartridges, commodities for
liquid-liquid partitioning relatively polar residues
Pesticide Analytical Manual Vol. ISECTION 302
302–2
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
Cleanup (C)
C1 (p. 302-21) Florisil column (4 g) cleanup, with relatively nonpolar
one methylene chloride eluant residues
C2 (p. 302-23) Charcoal/Celite/magnesium oxide polar residues
column cleanup
C3 (p. 302-25) Charcoal/silanized Celite column before HPLC
cleanup determination for
N-methylcarbamates
C4 (p. 302-27) C-18 cartridge cleanup before HPLC
determination for
N-methylcarbamates
C5 (p. 302-29) Florisil column cleanup, with relatively nonpolar
mixed ether eluants residues
C6 (p. 302-31) SAX/PSA cartridge cleanup polar and nonpolar
residues
Determination (D) Recommended Use
DG 1 (p. 302-33) GLC, 100% methyl siloxane residues with halogen.
column, 200 , EC detector sulfur, other moities
DG 2 (p. 302-35) GLC, 100% methyl siloxane residues with
column, 200 , FPD-P phosphorus
DG 3 (p. 302-37) GLC, 100% methyl siloxane residues with halogen
column, 200 , ELCD-X
DG 4 (p. 302-39) GLC, 100% methyl siloxane residues with nitrogen
column, 200 , ELCD-N
DG 5 (p. 302-41) GLC, 100% methyl siloxane residues with nitrogen
column, 200 , N/P detector or phosphorus
DG 6 (p. 302-43) GLC, 100% methyl siloxane biphenyl,
column, 160 , FID o-phenylphenol
DG 7 (p. 302-45) GLC, 100% methyl siloxane early eluting residues
column, 130 , EC detector with halogen, sulfur,
other moieties
DG 8 (p. 302-47) GLC, 100% methyl siloxane early eluting residues
column, 130 , FPD-P with phosphorus
DG 9 (p. 302-49) GLC, 100% methyl siloxane early eluting residues
column, 130 , ELCD-X with halogen
DG10 (p. 302-51) GLC, 100% methyl siloxane late eluting residues
column, 230 , EC detector with halogen, sulfur,
other moieties
DG11 (p. 302-53) GLC, 100% methyl siloxane late eluting residues
column, 230 , FPD-P with phosphorus
DG12 (p. 302-55) GLC, 100% methyl siloxane late eluting residues
column, 230 , ELCD-X with halogen
DG13 (p. 302-57) GLC, 50% phenyl, 50% methyl residues with halogen,
siloxane column, 200 , EC detector sulfur, other moieties
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–3
SECTION 302Pesticide Analytical Manual Vol. I
DG14 (p. 302-59) GLC, 50% phenyl, 50% methyl residues with phosphorus
siloxane column, 200 , FPD-P
DG15 (p. 302-61) GLC, 50% phenyl, 50% methyl residues with sulfur
siloxane column, 200 , FPD-S
DG16 (p. 302-63) GLC, 50% phenyl, 50% methyl residues with halogen
siloxane column, 200 , ELCD-X
DG17 (p. 302-65) GLC, 50% phenyl, 50% methyl residues with nitrogen
siloxane column, 200 , N/P or phosphorus
detector
DG18 (p. 302-67) GLC, 50% cyanopropylphenyl, residues with halogen,
50% methyl siloxane column, sulfur, other moieties
200 , EC detector
DG19 (p. 302-69) GLC, 50% cyanopropylphenyl, residues with phosphorus
50% methyl siloxane column,
200 , FPD-P
Pesticide Analytical Manual Vol. ISECTION 302
302–4
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
Figure 302
Recommended Approach: Nonfatty Foods
E2/E3
C1/C5
DG10
pyrethroids
DG6
biphenyl,
o-phenylphenol
DL1
N-methyl-
carbamates
DG2/14
DG3/16
DG4/5/17
DG15
DG12
residues
detectable
with
element-
selective
detectors
>75% water
E1/E5 E4/E6
C3/C4
<75% water>75% water
E7
C6
DG2
DG3
DG14
DG16
residues
detectable
with
element-
selective
detectors
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–5
SECTION 302Pesticide Analytical Manual Vol. I
VALIDATION
Many combinations of method modules are possible. The following combinations
have undergone interlaboratory validation and are recommended for use:
E1 + DG2, DG3
Validation report:
Sawyer, L.D. (1985) J. Assoc. Off. Anal. Chem. 68, 64-71. Collaborative study
lead-ing to AOAC official final action status for acephate, a-BHC, chlorpyrifos,
dieldrin, monocrotophos, and omethoate in lettuce, strawberries, and toma-
toes.
AOAC official method reference: Official Methods of Analysis of the AOAC (1990)
15th ed., 985.22.
E1 + C3 + DL1
Validation report:
Pardue, J.R. (April 1987) “Recoveries of N-Methyl Carbamates Using a Com-
bination of the Luke (PAM I, 232.4) and Krause (PAM I, 242.24b, 242.25)
Procedures,” LIB 3138, FDA, Rockville, MD
E2 + C1 + [temperature programmed GLC systems equivalent to]
DG1, DG7, DG10, and DG16
Validation report:
Griffitt, K.R., and Szorik, M.M. (Sept 1989) “The Analysis of 127 Total Diet
Items for Chlorinated Residues Using Luke/Solid Phase Extracts,” LIB 3366,
FDA, Rockville, MD
Pesticide Analytical Manual Vol. ISECTION 302
302–6
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–7
SECTION 302Pesticide Analytical Manual Vol. I
E1 EXTRACTION WITH ACETONE, LIQUID-LIQUID PARTITIONING WITH
PETROLEUM ETHER/METHYLENE CHLORIDE
References
Luke, M.A., et al. (1975) J. Assoc. Off. Anal. Chem. 58, 1020-1026
Luke, M.A., et al. (1981) J. Assoc. Off. Anal. Chem. 64, 1187-1195
Principles
Nonfatty sample is blended with acetone and filtered. Most nonionic residues are
extracted into aqueous acetone solution. Residues are transferred from aqueous
acetone to methylene chloride/petroleum ether by partitioning, with salt added to
aqueous layer after the first partitioning to aid transfer. Concentration step is
repeated in the presence of petroleum ether to remove all traces of methylene
chloride, then repeated again to produce final extract in acetone solution.
Apparatus
blender, high speed; explosion-proof Waring Blendor, 1 qt jar
Büchner funnel (Büchner), porcelain, 12 cm diameter
filter paper, Shark Skin
?
, to fit Büchner
long-stemmed funnel, glass, 4" diameter
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated receiving flask
separatory funnel (separator), 1 L
Reagents
acetone, distilled from all-glass apparatus
boiling chips, 20-30 mesh carborundum
glass wool, Pyrex, see Section 204 for handling directions
methylene chloride, distilled from all-glass apparatus
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Prewash filter paper with acetone to remove contaminants.
? Weigh 100 g chopped or blended sample into blender jar, add 200 mL
acetone, and blend 2 min at high speed.
? Filter with suction through 12 cm Büchner fitted with Shark Skin
?
paper;
collect extract in 500 mL suction flask. Filtration is normally complete in
<1 min. Continuation of vacuum for excessive period can reduce volume
of extract and cause error in calculation.
? Place 80 mL sample extract in 1 L separator, and add 100 mL petroleum
ether and 100 mL methylene chloride. Shake vigorously 1 min.
? Transfer lower aqueous layer to second 1 L separator.
Pesticide Analytical Manual Vol. ISECTION 302
302–8
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? Dry upper layer of first separator by passing through about 1.5" sodium
sulfate supported on washed glass wool in 4" funnel, collecting in K-D. (If
extract will be cleaned up directly with C3, charcoal/Celite column, collect
in vacuum rotary evaporator flask.)
? To separator with aqueous phase, add 7 g sodium chloride and shake
vigorously 30 sec until most of the sodium chloride is dissolved.
? Add 100 mL methylene chloride, shake 1 min, and dry lower organic phase
through same sodium sulfate.
? Extract aqueous phase with additional 100 mL methylene chloride and dry
as above. Rinse sodium sulfate with about 50 mL methylene chloride.
(If extract will be cleaned up directly with C3, proceed to concentration step
described there instead of evaporating in K-D as follows.)
? Add boiling chips to K-D and concentrate solvent in K-D; start evaporation
slowly by placing only receiver tube into steam. After 100-150 mL has
evaporated, concentrator may be exposed to more steam. When liquid level
in hot concentrator tube is about 2 mL, add 100 mL petroleum ether
through Snyder column and reconcentrate to about 2 mL. Add 50 mL
petroleum ether and repeat concentration step. Add 20 mL acetone, and
reconcentrate to about 2 mL. Do not allow solution to go to dryness during
any of the concentration steps. Adjust volume of extract to suitable definite
volume with acetone.
? Calculate equivalent sample weight in final solution:
mg sample equivalent
m L final extract
= 100 ·
80
200 + W – 10
1
mL final volume
·
where:
100 = g sample analyzed
80 = mL filtered extract taken for liquid-liquid partitioning
200 = mL acetone blended with 100 g sample
W = amount (mL) of water present in sample (Section 201; if data are not
available for particular raw agricultural commodity, use 85%)
10 = adjustment for water/acetone volume contraction.
Thus, when sample contains 85% water (85 mL/100 g) and final extract
volume is 7 mL, each m L contains:
4.15 mg sample equivalent
m L final extract
100 ·
80
200 + 85 – 10
1
7
· =
? Extract may be suitable, as is, for determination by GLC with selective
detectors (e.g., DG2, DG3). If co-extractives interfere with determination or
adversely affect chromatography, clean up extract with C1, C2, or C5 prior
to determination.
? Clean up extract with C1 or C5 prior to determination by electron capture
(DG1, DG7, etc.) or flame ionization detectors (DG6). Clean up extract with
C3 or C4 prior to determination by DL1 for N-methylcarbamates.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–9
SECTION 302Pesticide Analytical Manual Vol. I
E2 EXTRACTION WITH ACETONE, REMOVAL OF WATER WITH
40 G HYDROMATRIX
References
Luke, M.A., et al. (1975) J. Assoc. Off. Anal. Chem. 58, 1020-1026
Luke, M.A., et al. (1981) J. Assoc. Off. Anal. Chem. 64, 1187-1195
Hopper, M.L. (1988) J. Assoc. Off. Anal. Chem. 71, 731-734
Principles
Nonfatty sample is blended with acetone and filtered. Most nonionic residues are
extracted from nonfatty foods into aqueous acetone solution. Water is removed from
aqueous acetone solution by passing it through a column of specially treated
diatomaceous earth (Hydromatrix). Residues are eluted from column with methyl-
ene chloride. Up to 13.3 mL water, from 40 mL aqueous acetone extractant, is
adsorbed by the column, which is re-usable.
Apparatus
blender, high speed; explosion-proof Waring Blendor, 1 qt jar
Büchner funnel (Büchner), porcelain, 12 cm diameter
filter paper, Shark Skin
?
, to fit Büchner
chromatographic column, 25 mm id · 500 mm, Teflon stopcock
long-stemmed funnel, glass, 4" diameter
powder funnel, glass, 4" diameter
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated receiving flask
sieve, No. 30
Reagents
acetone, distilled from all-glass apparatus
buffer solution: 0.1 M (13.6 g/L) potassium phosphate monobasic (KH
2
PO
4
)
in water
Hydromatrix material (pelletized diatomaceous earth), Part No. 0019-8003,
Analytichem International, Harbor City, CA; also available through Varian
methylene chloride, distilled from all-glass apparatus
potassium phosphate monobasic, certified ACS grade
wire gauze, 40 mesh stainless steel
Directions
? Prepare Hydromatrix column:
– Cut two pieces stainless steel gauze into circles of diameter slightly
larger than chromatographic column id. Place one circle in bottom of
column.
– Place 50 g Hydromatrix material on No. 30 sieve and sieve thoroughly
to remove fines.
Pesticide Analytical Manual Vol. ISECTION 302
302–10
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
– Pour 40 g sieved Hydromatrix material into column with aid of powder
funnel. Tap end of column lightly on benchtop to settle material. Place
second stainless steel gauze circle on top of material in column.
– With stopcock fully open, wash column with 150 mL buffer solution.
– After buffer solution has passed into column and flow has slowed to 3-5
mL/min, wash column with 300 mL acetone. Adjust flow to 50-60 mL/
min after first 100 mL acetone has eluted.
– Wash column with 300 mL methylene chloride. Re-adjust flow to 50-60
mL/min after first 100 mL methylene chloride has eluted.
? Prewash filter paper with acetone to remove artifacts.
? Weigh 100 g chopped or blended sample into blender jar, add 200 mL
acetone, and blend 2 min at high speed.
? Filter with suction through 12 cm Büchner fitted with Shark Skin
?
paper;
collect extract in 500 mL suction flask. Filtration is normally complete in <1
min. Continuation of vacuum for excessive period can reduce volume of
extract and cause error in calculation.
? Prewash Hydromatrix column with 200 mL acetone followed by 200 mL
methylene chloride immediately before each use. Discard wash solvents.
? Place K-D under column. (If extract will be cleaned up directly with C3,
charcoal/Celite column, collect in vacuum rotary evaporator flask.) Trans
fer 40 mL filtered acetone extract to top of column. Let extract pass into
column until flow rate has slowed to <1 mL/min. Let column equilibrate 3
min at <1 mL/min.
? Add 50 mL methylene chloride to column. After that has passed into
column, add another 50 mL methylene chloride. After that has passed into
column, add another 200 mL methylene chloride.
? Collect eluate until flow rate has decreased to slow drip (about 1 mL/min).
Total elution time is 6-8 min.
(If extract will be cleaned up directly with C3, proceed to concentration step
described there instead of evaporating in K-D as follows.)
? Add boiling chips to K-D and concentrate solvent in K-D; start evaporation
slowly by placing only receiver tube into steam. After 100-150 mL has
evaporated, concentrator may be exposed to more steam. When liquid level
in hot concentrator tube is about 2 mL, add 100 mL petroleum ether
through Snyder column and reconcentrate to about 2 mL. Add 50 mL
petroleum ether and repeat concentration step. Add 20 mL acetone, and
reconcentrate to about 2 mL. Do not allow solution to go to dryness during
any of the concentration steps. Adjust volume of extract to suitable definite
volume with acetone.
? If extract will be cleaned up directly with C1, Florisil column, it is not
necessary to reconcentrate repeatedly (as above) to remove all traces of
methylene chloride. Instead, add boiling chips and concentrate solvent in
K-D to <5 mL. Without allowing K-D to cool, add 50 mL acetone through
Snyder column, and reconcentrate to suitable definite volume; allow to
cool.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–11
SECTION 302Pesticide Analytical Manual Vol. I
? Calculate equivalent sample weight in final solution:
mg sample equivalent
m L final extract
= 100 ·
40
200 + W – 10
1
mL final volume
·
where:
100 = g sample analyzed
40 = mL filtered extract taken for Hydromatrix partitioning
200 = mL acetone blended with 100 g sample
W = amount (mL) of water present in sample (Section 201; if data are
not available for particular raw agricultural commodity, use 85%)
10 = adjustment for water/acetone volume contraction.
Thus, when sample contains 85% water (85 mL/100 g) and final extract
volume is 5 mL, each m L contains:
2.9 mg sample equivalent
m L final extract
100 ·
40
200 + 85 – 10
1
5
· =
? Extract may be suitable, as is, for determination by GLC with selective
detectors (e.g., DG2, DG3). If co-extractives interfere with determination
or adversely affect chromatography, clean up extract with C1, C2, or C5
prior to determination.
? Clean up extract with C1 or C5 prior to determination by electron
capture (DG1, DG7, etc.) or flame ionization detectors (DG6). Clean up
extract with C3 or C4 prior to determination by DL1 for N-methyl-
carbamates.
? Re-use Hydromatrix column without further rinsing, unless any adsorbed
color elutes from column (after about 20 uses). When this occurs, restore
column as follows:
– Do not change stopcock setting. Flow rate will change due to
different solvent densities, but this is of no consequence.
– Wash column with 200 mL acetone, followed by sufficient volume
(200-300 mL) buffer solution to remove any color left on column.
Once color has been removed, elute with 300 mL acetone followed
by 200 mL methylene chloride. Column is now ready for re-use.
Pesticide Analytical Manual Vol. ISECTION 302
302–12
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
ALTERNATIVE:
E3 EXTRACTION WITH ACETONE, REMOVAL OF WATER WITH
25 G HYDROMATRIX
Reference
Palmer, R.E., and Hopper, M.L. (Nov. 1991) “Miniaturized Solid Phase Partition
Column for Determination of Organochlorine and Organophosphate Pesticides with
PAM I 232.4 (Luke procedure) Acetone Filtrate,” LIB 3613, FDA, Rockville, MD
Principles
Smaller size column of Hydromatrix reduces solvent use by 40% over E2, while still
removing water from same amount of extract. However, solution eluting from 25 g
Hydromatrix column may be cloudy, probably from a small amount of water; this
disappears during concentration. The 25 g column may also have a shorter lifetime
than the 40 g column. Results using the 25 g column may be somewhat less reliable
for certain chemicals; e.g., p,p'-dicofol and dicloran are recovered less reproducibly,
and >0.4 ppm methamidophos may be only partially recovered; elution with 300 mL
methylene chloride permits complete recovery of the latter.
Directions
? Follow directions of E2, except:
– Prepare Hydromatrix column from 25 g material instead of 40 g.
– Prewash Hydromatrix column with 100 mL acetone followed by 100 mL
methylene chloride immediately before each use.
– After transferring 40 mL filtered acetone extract to top of column, elute
with 25, 25, and 150 mL methylene chloride, instead of volumes used in
E2.
– Because amount of original sample and amount of filtered acetone
extract transferred to Hydromatrix column are the same as in E2, mg
sample equivalent is the same as E2.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–13
SECTION 302Pesticide Analytical Manual Vol. I
E4 EXTRACTION WITH WATER/ACETONE, LIQUID-LIQUID PARTITIONING
WITH PETROLEUM ETHER/METHYLENE CHLORIDE
Reference
Luke, M.A., and Doose, G.M. (1983) Bull. Environ. Contam. Toxicol. 30, 110-116
Principles
Low moisture nonfatty sample is blended with 35% water/acetone and filtered; the
presence of water in the extractant facilitates extraction of residues from the dry
product and dilutes co-extractives. Most nonionic residues are extracted into aqueous
acetone solution. Residues are transferred from aqueous acetone to organic solvent
methylene chloride/petroleum ether by partitioning, with salt added to the aqueous
layer after the first partitioning to aid transfer.
Apparatus
blender, high speed; explosion-proof Waring Blendor, 1 qt jar
Büchner funnel (Büchner), porcelain, 12 cm diameter
filter paper, Shark Skin
?
, to fit Büchner
long-stemmed funnel, glass, 4" diameter
grinder, suitable for reducing dry products to <20 mesh
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated receiving flask
separatory funnel (separator), 1 L
Reagents
acetone, distilled from all-glass apparatus
boiling chips, 20-30 mesh carborundum (optional)
glass wool, Pyrex; see Section 204 for handling directions
methylene chloride, distilled from all-glass apparatus
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
35% (v/v) water/acetone
Directions
? Prewash filter paper with acetone to remove artifacts.
? Grind sample containing <10% fat or oil to <20 mesh.
? Weigh 15 g ground sample into blender jar, add 350 mL 35% water/
acetone, and blend 2 min at high speed.
? Filter with suction through 12 cm Büchner fitted with Shark Skin
?
paper;
collect extract in 500 mL suction flask. Filtration is normally complete in
<1 min. Continuation of vacuum for excessive period can reduce volume
of extract and cause error in calculation.
? Place 80 mL sample extract in 1 L separator containing 100 mL methylene
chloride. Add 100 mL petroleum ether and shake vigorously 1 min.
Pesticide Analytical Manual Vol. ISECTION 302
302–14
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? Transfer lower aqueous layer to second 1 L separator.
? Dry upper organic layer of first separator by passing through about 1.5"
sodium sulfate supported on washed glass wool in 4" funnel, collecting
in K-D. (If extract will be cleaned up directly with C3, charcoal/Celite
column, collect in vacuum rotary evaporator flask.)
? To separator with aqueous phase, add 7 g sodium chloride and shake
vigorously 30 sec until most of the sodium chloride is dissolved.
? Add 100 mL methylene chloride, shake 1 min, and dry lower organic phase
through same sodium sulfate.
? Extract aqueous phase with additional 100 mL methylene chloride and dry
as above. Rinse sodium sulfate with about 50 mL methylene chloride.
(If extract will be cleaned up directly with C3, proceed to concentration step
described there instead of evaporating in K-D as follows.)
? Add boiling chips to K-D and concentrate solvent in K-D; start evaporation
slowly by placing only receiver tube into steam. After 100-150 mL has
evaporated, concentrator may be exposed to more steam. When liquid level
in hot concentrator tube is about 2 mL, add 100 mL petroleum ether
through Snyder column and reconcentrate to about 2 mL. Add 50 mL
petroleum ether and repeat concentration step. Add 20 mL acetone, and
reconcentrate to about 2 mL. Do not allow solution to go to dryness during
any of the concentration steps. Adjust volume of extract to suitable definite
volume with acetone.
? Calculate equivalent sample weight in final solution:
mg sample equivalent
m L final extract
= 15 ·
80
350
1
mL final volume
·
where:
15 = g sample analyzed
80 = mL filtered extract taken for liquid-liquid partitioning
350 = mL water/acetone blended with 15 g sample
Thus, when final extract volume is 2 mL, each m L contains:
1.7 mg sample equivalent
m L final extract
15 ·
80
350
1
2
· =
? Extract may be suitable, as is, for determination by GLC with selective
detectors (e.g., DG2, DG3). If co-extractives interfere with determination or
adversely affect chromatography, clean up extract with C1, C2, or C5 prior
to determination.
? Clean up extract with C1 or C5 prior to determination by electron capture
(DG1, DG7, etc.) or flame ionization detectors (DG6). Clean up extract with
C3 or C4 prior to determination by DL1 for N-methylcarbamates.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–15
SECTION 302Pesticide Analytical Manual Vol. I
ALTERNATIVE:
E5 EXTRACTION WITH ACETONE, LIQUID-LIQUID PARTITIONING WITH
ACETONE/METHYLENE CHLORIDE
Reference
Luke, M. A., and Doose, G. M. (1983) Bull. Environ. Contam. Toxicol. 30, 110-116
Principle
Polar pesticides such as methamidophos exhibit variable recoveries when petroleum
ether/dichloromethane is used in partitioning. Better recoveries are obtained when
acetone is substituted for petroleum ether. Transfer of polar pesticides from the
aqueous phase to the organic layer is further facilitated by adding sodium chloride
before, rather than after, the first partitioning step.
Directions
? Follow directions of E1 through blending and filtering. Then:
– Place 80 mL sample extract in 1 L separator, and add 100 mL acetone,
100 mL methylene chloride, and 7 g sodium chloride. Shake vigorously
1 min.
– Transfer lower aqueous layer to second 1 L separator.
– Dry upper organic layer of first separator by passing through about 1.5"
sodium sulfate supported on washed glass wool in 4" funnel, collecting
in K-D. (If extract will be cleaned up directly with C3, charcoal/
silanized Celite column, collect in vacuum rotary evaporator flask.)
– Add 100 mL methylene chloride, shake 1 min, and dry lower organic
phase through same sodium sulfate.
? Continue as in E1, “Extract aqueous phase with additional 100 mL
methylene chloride...”
ALTERNATIVE:
E6 EXTRACTION WITH WATER/ACETONE, LIQUID-LIQUID PARTITIONING
WITH ACETONE/METHYLENE CHLORIDE
Reference
Luke, M. A., and Doose, G. M. (1983) Bull. Environ. Contam. Toxicol. 30, 110-116
Principle
Polar pesticides such as methamidophos exhibit variable recoveries when petroleum
ether/methylene chloride is used in partitioning. Better recoveries are obtained
when acetone is substituted for petroleum ether. Transfer of polar pesticides from the
aqueous phase to the organic layer is further facilitated by adding sodium chloride
before, rather than after, the first partitioning step.
Pesticide Analytical Manual Vol. ISECTION 302
302–16
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
Directions
? Follow directions of E4 through blending and filtering. Then:
– Place 80 mL sample extract in 1 L separator containing 100 mL methyl-
ene chloride. Add 100 mL acetone and 7 g sodium chloride and shake
vigorously 1 min.
– Transfer lower aqueous layer to second 1 L separator.
– Dry upper organic layer of first separator by passing through about 1.5"
sodium sulfate supported on washed glass wool in 4" funnel, collecting in
K-D. (If extract will be cleaned up directly with C3, charcoal/silanized
Celite column, collect in vacuum rotary evaporator flask.)
– Add 100 mL methylene chloride, shake 1 min, and dry lower organic
phase through same sodium sulfate.
? Continue as in E4, “Extract aqueous phase with additional 100 mL methyl
ene chloride...”
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–17
SECTION 302Pesticide Analytical Manual Vol. I
E7 EXTRACTION WITH ACETONE AND SOLID PHASE EXTRACTION
CARTRIDGES, LIQUID-LIQUID PARTITIONING
Reference
Luke, M. A., et al. (Sept. 1994) “An Improved Variation of the Luke Multiresidue
Pesticide Procedure for the Analysis of Fruits and Vegetables Using Solid Phase
Extraction Cartridges and Element Selective Gas Chromatographic Detectors,” LIB
3896, FDA, Rockville, MD
Apparatus
blender, high speed; explosion-proof Waring Blendor, 1 qt jar
Büchner funnel (Büchner), porcelain, 12 cm diameter
filter paper, Shark Skin
?
, to fit Büchner
500 mL suction flask
long-stemmed funnel, glass, 4" diameter
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated receiving flask
separatory funnel (separator), 1 L
75 mL Bond Elut reservoir or equivalent
25 mm syringe filter, 0.45 m m Nylon 66, with 1 m m prefilter
tC-18 Solid Phase Extraction (SPE) cartridge, 500 mg
Reagents
acetone, distilled from all-glass apparatus
boiling chips, 20-30 mesh carborundum
eluant, water/acetone, 30% (v/v)
glass wool, Pyrex, see Section 204 for handling directions
methylene chloride, distilled from all-glass apparatus
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Prewash filter paper with acetone to remove contaminants.
? Weigh 100 g chopped or blended sample into blender jar, add 200 mL
acetone, and blend 2 min at high speed.
? Filter with suction through 12 cm Büchner fitted with Shark Skin
?
paper;
collect extract in 500 mL suction flask. Continuation of vacuum for
excessive period can reduce volume of extract and cause error in calcula-
tion.
? Attach 0.45 m m Nylon cartridge filter to bottom of 75 mL reservoir; attach
tC-18 SPE cartridge to outlet of cartridge filter.
? Wash system with 40 mL acetone, followed by 10 mL eluant. Discard
washes.
Pesticide Analytical Manual Vol. ISECTION 302
302–18
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? Measure 40 mL sample extract and place into reservoir. Elute extract
at 3 to 5 mL/min, with air pressure, into 1 L separatory funnel; do not allow
level of extract to go below bottom of reservoir.
? Rinse graduated cylinder used for transfer with 10 mL 30% water/acetone;
place rinse into reservoir and elute to column dryness.
? Add 50 mL acetone and 100 mL methylene chloride to separatory funnel
and shake vigorously 1 min. Let separator stand 5-10 min to allow layers to
separate.
? Dry lower organic layer of first separator by passing through about 1.5"
sodium sulfate supported on washed glass wool in 4" funnel, collecting
in K-D.
? Add 100 mL acetone and 100 mL methylene chloride to separator and
repeat shaking. Let separator stand 5-10 min.
? Drain lower organic layer through sodium sulfate into separator. (Sugar
content of fruit samples may result in aqueous phase’s being the lower layer.
In that case, add 5-10 mL methylene chloride and repeat shaking.) Rinse
sodium sulfate with about 50 mL methylene chloride.
? Add boiling chips to K-D and concentrate solvent in K-D; start evaporation
slowly by placing only receiver tube into steam. After 100-150 mL has
evaporated, concentrator may be exposed to more steam. Concentrate
solvent to 2-3 mL. After cooling, remove tube from K-D and adjust volume
to 5 mL with acetone.
? Calculate equivalent sample weight in final solution:
mg sample equivalent
m L final extract
= 100 ·
40
200 + W – 10
1
mL final volume
·
where:
100 = g sample analyzed
40 = mL filtered extract taken for liquid-liquid partitioning
200 = mL acetone blended with 100 g sample
W = amount (mL) of water present in sample (Section 201; if data
are not available for particular raw agricultural commodity,
use 85%)
10 = adjustment for water/acetone volume contraction.
Thus, when sample contains 85% water (85 mL/100 g) and final
extract volume is 5 mL, each uL contains:
2.9 mg sample equivalent
m L final extract
100 ·
40
200 + 85 – 10
1
5
· =
? Clean up extract with C6 prior to determination.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–19
SECTION 302Pesticide Analytical Manual Vol. I
C1 FLORISIL COLUMN (4 G) CLEANUP, WITH ONE METHYLENE CHLORIDE
ELUANT
References
Griffitt, K.R., et al. (July 1983) “Miniaturized Florisil Column Cleanup of Chlorinated
and Organophosphate Eluates in Total Diet Samples,” LIB 2722, FDA, Rockville, MD
Griffitt, K.R., and Szorik, M.M. (Sept. 1989) “The Analysis of 127 Total Diet
Items for Chlorinated Residues Using Luke/Solid Phase Extracts,” LIB 3366, FDA,
Rockville, MD
Principle
Residues in solution are separated from sample co-extractives on a small column of
Florisil adsorbent, eluting with a single eluant.
Apparatus
chromatographic column, 10 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
Kuderna-Danish concentrator (K-D), 125 or 250 mL, with Snyder column, two-
ball micro-Snyder column, graduated or volumetric receiving flask
Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distillation
directions
Florisil, PR grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
hexane, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
eluant: 50% methylene chloride/1.5% acetonitrile/48.5% hexane (v/v/v).
Pipet 15 mL acetonitrile into 500 mL methylene chloride and dilute
with hexane. Allow mixture to reach room temperature and adjust to
1 L with hexane.
Directions
? Place activated Florisil (weight = 110/lauric acid value · 4 g) in 10 mm
chromatographic column; add about 2 cm sodium sulfate. Completely
open stopcock and tap column to settle adsorbent. Prewet column with 15
mL hexane. Do not allow column to go dry. Place K-D with volumetric or
graduated receiving flask under column to receive eluate.
? Dilute extract with hexane to produce solution of 10% acetone/hexane.
Volumes depend on concentration of extract, volume taken for cleanup;
e.g., dilute 1 mL E1 extract, previously concentrated to 7 mL acetone, to
10 mL with hexane.
? Transfer solution to Florisil column, letting it pass through at about 5 mL/
min. Rinse container with two 3 mL portions hexane, transfer rinsings to
column, and rinse walls of chromatographic tube with additional small
portions hexane.
? Elute column at about 5 mL/min with 50 mL eluant.
Pesticide Analytical Manual Vol. ISECTION 302
302–20
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? Add boiling chip to K-D and concentrate eluate to suitable definite volume.
For example, if 1 mL E1 extract (equivalent to 4.15 mg/mL) was cleaned up,
concentrate Florisil eluate to 1 mL for same final concentration.
When volume <5 mL is needed, use two-ball micro-Snyder or micro-
Vigreaux column during evaporation.
? Use appropriate determinative steps, such as DG1 or DG13, DG6, DG7, and
DG10, to identify and measure residues.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–21
SECTION 302Pesticide Analytical Manual Vol. I
C2 CHARCOAL/CELITE/MAGNESIUM OXIDE COLUMN CLEANUP
References
Luke, M.A., and Doose, G.M. (1983) Bull. Environ. Contam. Toxicol. 30, 110-116
Hardy, R.P. (Fall 1984) “Recoveries of Organophosphorus Compounds Through the
Modified Storherr Method Using Charcoal Columns With and Without Magnesium
Oxide,” LIB 2860, FDA, Rockville, MD
Principles
Polar residues in solution are separated from sample co-extractives on a column of
charcoal/Celite/magnesium oxide; cleanup may be necessary for subsequent exami-
nation of extract with selective detectors. Aromatic residues are not eluted with this
system and must be determined in extract cleaned up by C1, Florisil column.
Magnesium oxide may be eliminated to prevent destruction of sensitive residues (e.g.,
acephate) without diminishing recoveries of other residues normally eluted.
Apparatus
chromatographic column, 22 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated or volumetric receiving flask
Reagents
acetone, distilled from all-glass apparatus
adsorbent mixture, 1:4:2 (w/w/w) charcoal/Celite 545/magnesium oxide or
1:4 (w/w) charcoal/Celite 545
Celite 545. To prepare, slurry about 500 g with distilled water, heat on steam
bath about 30 min, and filter with suction. Dry overnight at l05-l30 C and
pulverize to pass No. 60 sieve. Store in closed jar.
charcoal, Darco G60 or Norite S.G. Extra
glass wool, Pyrex; see Section 204 for handling directions
magnesium oxide, 200 mesh, adsorptive grade (optional)
methylene chloride, distilled from all-glass apparatus
eluant: 2:1 (v/v) acetone/methylene chloride
Directions
? Place about 1" Celite 545 in column, then add 6 g adsorbent mixture, and
top with large plug glass wool.
? Tamp column down firmly and add about 25 mL methylene chloride.
Force solvent through column with air pressure until top of solvent
reaches top of column. Discard solvent.
? Transfer sample extract quantitatively to column with small portions
methylene chloride and force solvent through as before, collecting in
K-D.
? Elute with 200 mL 2:1 acetone/methylene chloride; force through as
before.
Pesticide Analytical Manual Vol. ISECTION 302
302–22
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? Mix contents of K-D, add boiling chips, and concentrate solvent; start
evaporation slowly by placing only receiver tube into steam. After 100-150
mL has evaporated, concentrator may be exposed to more steam. When
liquid level in hot concentrator tube is about 2 mL, add 100 mL petroleum
ether through Snyder column and reconcentrate to about 2 mL. Add 50 mL
petroleum ether and repeat concentration step. Add 20 mL acetone, and
reconcentrate to about 2 mL. Do not allow solution to go to dryness during
any of the concentration steps. Adjust volume of extract to suitable definite
volume with acetone.
? If magnesium oxide is not used, a white precipitate may form if extract is
concentrated to <2 mL; this should not affect GLC.
? Use appropriate determinative steps or confirmatory steps, such as GLC
with mass spectrometric detection.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–23
SECTION 302Pesticide Analytical Manual Vol. I
C3 CHARCOAL/SILANIZED CELITE COLUMN CLEANUP
References
Krause, R.T. (1980) J. Assoc. Off. Anal. Chem. 63, 1114-1124
Pardue, J.R. (May 1987) “Recoveries of N-Methyl Carbamates Using a Combination
of the Luke (PAM I, 232.4) and Krause (PAM I, 242.24b, 242.25) Procedures,” LIB
3138, FDA, Rockville, MD
Principle
Residues in solution are separated from sample co-extractives on a column of charcoal
and Celite, cleaning up the extract sufficiently for subsequent determination by
HPLC system DL1.
Apparatus
chromatographic column, 22 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
evaporator, vacuum rotary, as described in Section 401 E1
flasks, round-bottom (r-b), 250 and 500 mL, 1 L
magnetic stirrer, star, 10 mm diameter · 8 mm
vacuum adapter, side arm, with TS bottom joint to fit in 500 mL r-b flask
Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distillation
directions
Celite 545, silanized and prepared for use as directed in Section 401 C1
charcoal (Nuchar S-N), produced by Westvaco Corp. and available from
Eastman Kodak, Cat. No. 118 0454, purified as directed in Section 401 C1
glass wool, Pyrex; see Section 204 for handling directions
methanol, distilled from all-glass apparatus
methylene chloride, distilled from all-glass apparatus
toluene, distilled from all-glass apparatus
eluant: 25% (v/v) toluene/acetonitrile
Directions
? Test charcoal/silanized Celite column as described in Section 401 C1.
? To the extract in r-b flask, add star magnetic stirrer. Place 250 mL TS 24/
40 trap on 1 L r-b flask and attach to vacuum rotary evaporator.
? Circulate refrigerated (-15 C) 1+1 water/ethylene glycol through evapo-
rator condensing coils; maintain receiving flask at -15 C by immersion in
refrigerated bath.
? Apply vacuum slowly to minimize frothing by regulating with needle valve.
After full vacuum is applied, slowly place flask in 35 C water bath.
? Remove r-b flask from evaporator immediately after last traces of solution
have evaporated and add 10 mL methylene chloride to r-b flask.
Pesticide Analytical Manual Vol. ISECTION 302
302–24
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? Fit one-hole No. 5 rubber stopper onto tip of chromatographic column, add
side arm vacuum adapter and 500 mL r-b flask, open stopcock, and connect
apparatus to vacuum line.
? Place 0.5 g silanized Celite 545 in chromatographic column, tamp, add 5 g
charcoal/Celite 545 (1+4) mixture, and tamp again. Add 1-2 cm glass wool
plug on top of adsorbent.
? Prewash column with 50 mL 25% toluene/acetonitrile eluant. Close stop-
cock when prewash solution is about 0.5 cm from top of glass wool.
? Disconnect vacuum, discard solution in r-b flask, and reconnect flask to
apparatus.
? Transfer 10 mL methylene chloride extract to column and let pass through
column at 5 mL/min.
? Wash 1 L r-b flask with 10 mL methylene chloride and then with 25 mL
eluant. Transfer each separately to column and elute each to top of glass
wool before adding next solution.
? Add 100 mL eluant and elute column at 5 mL/min. Turn off stopcock when
top of eluant reaches top of glass wool.
? Evaporate solution in 500 mL r-b flask just to dryness using vacuum
evaporator as above. Remove flask from evaporator immediately after all
solution has evaporated.
? Immediately pipet 5 mL methanol into 500 mL r-b flask to dissolve residue.
Cleaned up extract contains concentration of sample equivalent (mg/m L)
equal to amount of sample in extract taken for cleanup, divided by 5. For
example, if entire E1 extract of commodity with 85% water is used, 29 g
sample equivalent is cleaned up, i.e., 100 g · 80/(200 + 85 - 10); final concen-
tration of cleaned up extract is 5.8 mg/m L (29 g/5 mL).
? Use determinative step DL1 or DL2 (Section 401) to determine
N-methylcarbamates, except use 20 m L injection loop instead of 10 m L
loop specified.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–25
SECTION 302Pesticide Analytical Manual Vol. I
C4 C-18 CARTRIDGE CLEANUP
Reference
Sharp, K.B., and Bramlett, C.L. (Dec. 1983) “Analysis for Carbamate Residues in Fresh
Produce,” LIB 2778, FDA, Rockville, MD
Principle
Residues in solution are separated from sample co-extractives on a C-18 solid phase
extraction cartridge, cleaning up the extract sufficiently for subsequent determina-
tion by HPLC system DL1.
Apparatus
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated receiving flask
volumetric flask, 5 mL
Reagents
cartridge (solid phase extraction type), C-18, 2.8 mL
methanol, distilled from all-glass apparatus
Directions
? Concentrate extract in K-D to 2 mL. Evaporate almost to dryness (about 0.1
mL) under current of nitrogen.
? Prewet C-18 cartridge with methanol and discard solvent.
? Dissolve residue in receiving flask with 2 mL methanol and transfer
quantitatively onto prewet C-18 cartridge. Collect eluate from cartridge in
5 mL volumetric flask.
? Elute cartridge with additional methanol until collected volume is almost
5 mL; add methanol to make volume 5.0 mL. Cleaned up extract contains
concentration of sample equivalent (mg/m L) equal to amount of sample
in extract taken for cleanup, divided by 5. For example, if entire E1 extract
of commodity with 85% water is used, 29 g sample equivalent is cleaned up,
i.e., 100 g · 80/(200 + 85 - 10); final concentration of cleaned up extract
is 5.8 mg/m L (29 g/5 mL).
? Use determinative step DL1 or DL2 (Section 401) to determine
N-methylcarbamates, except use 20 m L injection loop instead of 10 m L loop
specified.
Pesticide Analytical Manual Vol. ISECTION 302
302–26
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–27
SECTION 302Pesticide Analytical Manual Vol. I
C5 FLORISIL COLUMN CLEANUP, WITH MIXED ETHER ELUANTS
Reference
Luke, M.A., et al. (1975) J. Assoc. Off. Anal. Chem. 58, 1020-1026
Principles
Residues in solution are separated from sample co-extractives on a column of Florisil
adsorbent; cleanup is usually necessary for subsequent examination of extract with
DG1, electron capture detector.
Apparatus
chromatographic column, 22 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
graduated cylinder (graduate), glass-stoppered (g-s), 100 mL
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, volumetric or graduated receiving flask
Reagents
boiling chips, 20-30 mesh carborundum
eluants: 15% (v/v) ethyl ether/petroleum ether
50% (v/v) ethyl ether/petroleum ether
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preservative;
see Section 204 for peroxide test
Florisil, PR grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
petroleum ether, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Place activated Florisil (4" or weight determined by lauric acid value) in 22
mm id column; add about 0.5" sodium sulfate. Prewet column with 40-50
mL petroleum ether. Place K-D with volumetric or graduated receiving
flask under column to receive eluate.
? Dilute concentrated extract to 10 mL with acetone and transfer to 100 mL
g-s graduate, using petroleum ether to rinse. Dilute to 100 mL with
petroleum ether; stopper and mix well.
? Transfer diluted extract solution to column letting it pass through at about
5 mL/min.
? Elute column at about 5 mL/min with 200 mL 15% ethyl ether/petroleum
ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 50% ethyl ether/
petroleum ether eluant.
? Add boiling chips to K-Ds and concentrate to suitable definite volume. For
example, if entire E1 extract of commodity with 85% water is used, and
final volume is 5 mL, final concentration of cleaned up extract is 5.8 mg/
m L, i.e., 100 g · 80/(200 + 85 - 10) = 29 g; 29 g/5 mL = 5.8 mg/m L.
Pesticide Analytical Manual Vol. ISECTION 302
302–28
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
? When volume <5 mL is needed, use two-ball micro-Snyder or micro-
Vigreaux column during final evaporation in receiving flask.
? Use appropriate determinative steps, such as DG1 or DG13, DG6, DG7, and
DG10, to identify and measure residues.
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–29
SECTION 302Pesticide Analytical Manual Vol. I
C6 SAX/PSA CARTRIDGE CLEANUP
Reference
Luke, M. A., et al. (Sept. 1994) “An Improved Variation of the Luke Multiresidue
Pesticide Procedure for the Analysis of Fruits and Vegetables Using Solid Phase
Extraction Cartridges and Element Selective Gas Chromatographic Detectors,” LIB
3896, FDA, Rockville, MD
Principle
SAX and PSA cartridges provide the improved cleanup required for determination
with capillary and megabore GC columns; both polar and nonpolar residues can be
recovered.
Apparatus
75 mL Bond Elut reservoir or equivalent
25 mm syringe filter, 0.45 m m Nylon 66 with 1 m m prefilter
SAX SPE cartridge or equivalent, 500 mg
PSA SPE cartridge or equivalent, 500 mg
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated or volumetric receiving flask
Reagents
acetone, distilled from all-glass apparatus
petroleum ether, distilled from all-glass apparatus
acetone+petroleum ether, 1+2
Directions
? Attach 0.45 m m filter to bottom of 75 mL reservoir. Attach SAX or
equivalent cartridge to filter, and attach PSA or equivalent cartridge to first
cartridge.
? Wash cartridges with 40 mL acetone; follow with 10 mL acetone+petroleum
ether. Discard washes.
? Dilute the 5.0 mL concentrated acetone extract from E7 with 10 mL
petroleum ether and mix. Transfer to reservoir, and elute dropwise with
air pressure.
? Rinse tube with five 10 mL portions acetone+petroleum ether. Elute each
rinse when the previous solvent has reached top of column.
? Mix contents of K-D, add boiling chips, and concentrate solvent; start
evaporation slowly by placing only receiver tube into steam. When liquid
level in hot concentrator tube is about 2 mL, add 100 mL petroleum ether
through Snyder column and reconcentrate to about 2 mL. Add 50 mL
petroleum ether and repeat concentration step. Carefully add 25 mL
acetone and reconcentrate to about 2 mL. Do not allow solution to go to
dryness during any of the concentration steps. Adjust volume of extract to
suitable definite volume with acetone.
? Use appropriate determinative steps, such as DG2, DG3, DG14, or DG16,
to identify and measure residues.
Pesticide Analytical Manual Vol. ISECTION 302
302–30
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–31
or
DETERMINATION
Inject concentrated extract equivalent to 20 mg (whole high moisture product) into
the following GLC systems for determination of residues. (Although AOAC collabo-
rative study for this method involved injection of 12 mg sample equivalent, experience
since then has proven that GLC systems can tolerate routine injections equivalent to
20 mg of most nonfatty foods.)
Extract not cleaned up prior to determination:
DG2 or DG14 organophosphorus residues; large amounts of sulfur may
interfere
DG3 or DG16 organohalogen residues
DG4 organonitrogen residues; selective to nitrogen, but co-extrac-
tives may contain nitrogen
DG5 or DG17 organonitrogen and organophosphorus residues
DG15 organosulfur residues; large amounts of phosphorus may
interfere
DG12 late eluting organohalogen residues, especially pyrethroids
Additional recommended determinations:
Extract not cleaned up prior to determination:
DG8 early eluting organophosphorus residues
DG11 late eluting organophosphorus residues
DG9 early eluting organohalogen residues
Extract cleaned up on Florisil column, C1 or C5:
DG1 or DG13 residues with halogen, sulfur, or other moieties
DG7 early eluting residues with halogen, sulfur, or other moieties
DG10 late eluting residues, especially synthetic pyrethroids
DG6 o-phenylphenol and biphenyl
Inject concentrated extract equivalent to about 58-116 mg (whole high moisture
product) cleaned up by C3 (charcoal/Celite column) or C4 (C-18 cartridge) into
following HPLC system:
DL1 N-methylcarbamates (determinative step described in
Section 401)
For accurate quantitation, reference standards should be dissolved in same solvent as
concentrated extract, only peaks >10% FSD should be measured, and peak sizes of
residue and reference standard should match within – 25%.
See Chapter 5 for additional information about operation of GLC systems; Section
504 provides information about quantitation of residues.
See Chapter 6 for additional information about operation of HPLC systems; Section
606 provides information about quantitation of residues.
Pesticide Analytical Manual Vol. ISECTION 302
302–32
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
See Section 205 for additional information about reference standards.
See Section 104 for additional information about reporting residues and determining
compliance with regulations.
See Section 105 for additional information about analytical limits of quantitation.
CONFIRMATION
After residues have been tentatively identified and quantitated by comparison to
appropriate reference standards, confirm identity according to principles discussed
in Section 103. Use appropriate tables of data (PESTDATA, tables accompanying
each method, Index to Methods) to choose the most appropriate determinative
steps and/or alternative methods for confirmation.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–33
DG1 GLC, 100% METHYL SILOXANE, 200
C, EC
Applicability
Determinative step is applicable to residues containing halogen, sulfur, or other
electrophilic moieties. It is a general purpose system, but subject to interferences by
nonpesticides.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of p,p'-DDT is 3.1 – 0.06.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4.0 – 0.5
min (about 20 mL/min).
Injector temperature: 220-250 C
Detector
Electron Capture (EC)
Detector Operating Conditions:
350 C
Make-up gas: nitrogen or argon/methane (95:5), at 30 mL/min
See Section 503 B for other information about EC detector operation.
Set detector electronics (amplification, attenuation) so that response to 0.15 ng
chlorpyrifos (or an amount within the detector’s linear range) is 50% full scale
deflection (FSD).
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column). Re-
sponse data in Appendix I are based on detector sensitivity of 50% FSD to 1.5 ng
chlorpyrifos.
Example chromatogram is on next page. Also see Figures 504-c, d, e, and f.
Pesticide Analytical Manual Vol. ISECTION 302
302–34
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
DG1
Chromatogram of: 1) 0.15 ng dicloran, 2) 0.10 ng heptachlor, 3) 0.19 ng chlorpyrifos, 4) 0.31 ng captan,
5) 0.14 ng endosulfan I, 6) 0.18 ng endrin, and 7) 0.20 ng p,p￠ -DDT at the conditions described.
510
min
1
2
3
4
5
6
7
0
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–35
DG2 GLC, 100% METHYL SILOXANE, 200
C, FPD-P
Applicability
Determinative step is applicable to residues containing phosphorus. It is particularly
useful for residues such as organophosphate pesticides.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked.
For example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of ethion is 2.56 – 0.05.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4.0 – 0.5
min (about 20 mL/min).
Injector temperature: 220-250 C
Detector
Flame photometric, phosphorus mode (FPD-P)
Detector Operating Conditions:
225-250 C
See Section 503 C for other information about FPD operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
A properly functioning system will give a response to 1.5 ng omethoate of ? 50%
FSD.
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–36
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
1
2
3
4
5
6
0
DG2
Chromatogram of: 1) 0.85 ng acephate, 2) 1.73 ng omethoate, 3) 0.68 ng monocrotophos, 4) 1.30 ng
malathion, 5) 1.27 ng chlorpyrifos, and 6) 1.26 ng ethion at the conditions described; helium carrier gas
flow was 15 mL/min, with 15 mL/min make-up gas being added before the detector. Detector gas flows:
100 mL/min hydrogen, 130 mL/min air.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–37
DG3 GLC, 100% METHYL SILOXANE, 200
C, ELCD-X
Applicability
Determinative step is applicable to residues containing halogen. It is particularly
useful for residues such as chlorinated hydrocarbon pesticides and polychlorinated
biphenyls.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of p,p'-DDT is 3.1 – 0.06.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4.0 – 0.5
min (about 20 mL/min).
Injector temperature: 220-250 C
Detector
Electroconductivity, halogen mode (ELCD-X)
Detector Operating Conditions:
Base temperature 250 C; furnace temperature 900 C (or as specified in operat-
ing manual)
Reactor gas: hydrogen, flow as required by specific detector model; see operating
manual
See Section 503 D for other information about ELCD operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–38
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
5015
min
1
2
3
4
5 6
7
10
DG3
Chromatogram of: 1) 1.44 ng dicloran, 2) 0.98 ng heptachlor, 3) 1.87 ng chlorpyrifos, 4) 2.99 ng
captan, 5) 1.37 ng endosulfan I, 6) 1.77 ng endrin, and 7) 1.91 ng p,p￠ -DDT at the conditions described.
Hydrogen reactor gas flow: 40 mL/min, n-propanol electrolyte: 0.3 mL/min.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–39
DG4 GLC, 100% METHYL SILOXANE, 200
C, ELCD-N
Applicability
Determinative step is applicable to residues containing nitrogen. It may be useful for
confirmation of residues such as triazines (atrazine, simazine, etc.) and triazoles
(propiconazole, diclobutrazole, etc.).
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C isothermal
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4.0 – 0.5
min (about 20 mL/min).
Injector temperature: 220-250 C
Detector
Electroconductivity, nitrogen mode (ELCD-N)
Detector Operating Conditions:
Base temperature 250 C; furnace temperature 900 C (or as specified in operat-
ing manual)
Reactor gas: hydrogen, flow as required by specific detector model; see operating
manual
See Section 503 D for other information about ELCD operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PEST-
DATA (many data in PESTDATA were collected using equivalent packed column).
No chromatogram currently available.
Pesticide Analytical Manual Vol. ISECTION 302
302–40
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–41
DG5 GLC, 100% METHYL SILOXANE, 200
? C, N/P
Applicability
Determinative step is applicable to residues containing nitrogen. It is particularly
useful for residues such as triazines and triazoles.
Column:
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of ethion is 2.56 – 0.05.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4.0 – 0.5
min (about 20 mL/min).
Injector temperature: 220-250 C
Detector
Alkali bead detector, nitrogen selective (N/P)
Detector Operating Conditions:
250 C
See Section 503 E for other information about N/P detector operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
A properly functioning system will give a response to 1.5 ng omethoate of ? 50%
FSD.
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–42
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
5
min
0
1
2
3
4
5
DG5
Chromatogram of: 1) 1.0 ng atrazine, 2) 7.5 ng carbaryl, 3) 1.5 ng chlorpyrifos, 4) 2.5 ng procyazine,
and 5) 5.0 ng imazalil at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–43
DG6 GLC, 100% METHYL SILOXANE, 130 C, FID
Applicability
Determinative step is applicable to residues containing no elements to which element-
selective detectors respond. It is particularly useful for residues such as biphenyl and
o-phenylphenol.
Column
Wide bore capillary, 30 m ￥ 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
130 C isothermal
Carrier gas: helium, about 20 mL/min. At these conditions, chlorpyrifos elutes
in about 16 min, and biphenyl and o-phenylphenol elute in <2 min.
Injector temperature: 220-250 C
Detector
Flame ionization detector (FID)
Detector Operating Conditions:
300 C
detector gases: hydrogen, 30 mL/min, air, 300 mL/min
set detector electronics (amplification, attenuation) so that response to
50 ng o-phenylphenol is 50% full scale deflection (FSD).
Other Considerations
FID is nonselective and will respond to large quantities of any co-extractive.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–44
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
50
min
1
2
DG6
Chromatogram of: 1) 20 ng biphenyl and 2) 53 ng o-phenylphenol at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–45
DG7 GLC, 100% METHYL SILOXANE, 130
C, EC
Applicability
Determinative step is applicable to residues of high volatility (early elution) and
containing halogen, sulfur, or other electrophilic moieties. It is particularly useful for
residues such as benfluralin and sulfallate.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
130 C isothermal
Carrier gas: helium; adjust flow rate while column temperature is 200 C so that
chlorpyrifos elutes in about 4.0 – 0.5 min; then change column temperature
without changing flow controller.
Injector temperature: 220-250 C
Detector
Electron Capture (EC)
Detector Operating Conditions:
350 C
Make-up gas: nitrogen or argon/methane (95:5), at 30 mL/min
See Section 503 B for other information about EC detector operation.
While column temperature is 200 C, set detector electronics (amplification,
attenuation) so that response to 0.15 ng chlorpyrifos (or an amount within the
detector’s linear range) is 50% full scale deflection; then change column tempera-
ture without changing electronics.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–46
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
5 15
min
2
1
100
DG7
Chromatogram of: 1) 0.18 ng benfluralin and 2) 0.09 ng sulfallate at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–47
DG8 GLC, 100% METHYL SILOXANE, 130
C, FPD-P
Applicability
Determinative step is applicable to residues of high volatility (early elution) and
containing phosphorus. It is particularly useful for residues such as mevinphos,
acephate, demeton, and dicrotophos.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
130 C isothermal
Carrier gas: helium; adjust flow rate while column temperature is 200 C so that
chlorpyrifos elutes in about 4.0 – 0.5 min; then change column temperature
without changing flow controller.
Injector temperature: 220-250 C
Detector
Flame photometric, phosphorus mode (FPD-P)
Detector Operating Conditions:
225-250 C
See Section 503 C for other information about FPD operation.
While column temperature is 200 C, set detector electronics (amplification,
attenuation) so that response to 1.5 ng chlorpyrifos is 50% full scale deflection;
then change column temperature without changing electronics.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–48
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
15
1
2
3
0
DG8
Chromatogram of: 1) 2.0 ng methamidophos, 2) 2.0 ng acephate, and 3) 4.0 ng dicrotophos
at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–49
DG9 GLC, 100% METHYL SILOXANE, 130
C, ELCD-X
Applicability
Determinative step is applicable to residues of high volatility (early elution) and
containing halogen. It is particularly useful for residues such as the methyl esters of
dicamba, MCPA, mecoprop, dichlorprop, and silvex.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
130 C isothermal
Carrier gas: helium, about 20 mL/min
Injector temperature: 220-250 C
Detector
Electroconductivity, halogen mode (ELCD-X)
Detector Operating Conditions:
Base temperature 250 C; furnace temperature 900 C (or as specified in operat-
ing manual)
Reactor gas: hydrogen, flow as required by specific detector model; see operating
manual
See Section 503 D for other information about ELCD operation.
Set detector electronics (amplification, attenuation) so that response to 0.5 ng
pentachlorobenzene is 50% full scale deflection.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–50
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
min
51015 200
1
2
3
4
DG9
Chromatogram of: 1) 1.0 ng dicamba methyl ester, 2) 3.0 ng MCPA methyl ester,
3) 1.5 ng dichlorprop methyl ester, and 4) 2.0 ng silvex methyl ester at the conditions described,
except that carrier gas was hydrogen at 25 mL/min. Hydrogen reactor gas flow: 35 mL/min,
n-propanol electrolyte 0.5 mL/min. Pentachlorobenzene eluted in 6.9 min at these conditions,
and 0.3 ng pentachlorobenzene caused 40% FSD detector response.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–51
DG10 GLC, 100% METHYL SILOXANE, 230
C, EC
Applicability
Determinative step is applicable to residues of low volatility (late elution) and
containing halogen, sulfur, or other electrophilic moieties. It is particularly useful for
residues such as pyrethroids, with halogen (permethrin, fenvalerate, deltamethrin)
or without halogen (tetramethrin).
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
230 C isothermal; if necessary, adjust temperature so that relative retention time
(rrt) to phosalone of cis permethrin is about 1.55.
Carrier gas: helium; adjust flow rate so that phosalone elutes in about 8 min (about
18 mL/min).
Injector temperature: 250 C
Detector
Electron Capture (EC)
Detector Operating Conditions:
350 C
Make-up gas: nitrogen or argon/methane (95:5), at 30 mL/min
See Section 503 B for other information about EC detector operation.
Set detector electronics (amplification, attenuation) so that response to 0.5 ng
phosalone is 50% full scale deflection (FSD).
Other Considerations
Detector sensitivity must be sufficient to measure residues of pyrethroids at ￡ 0.1 ppm,
where some tolerances are set.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–52
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
15 20 25 300
1 2 3 4 5
DG10
Chromatogram of: 1) 3.5 ng tetramethrin, 2) 2.3 ng permethrin, 3) 2.1 ng cypermethrin,
4) 1.9 ng fenvalerate, and 5) 2.2 ng deltamethrin at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–53
DG11 GLC, 100% METHYL SILOXANE, 230
C, FPD-P
Applicability
Determinative step is applicable to residues of low volatility (late elution) and
containing phosphorus. It is particularly useful for residues such as some organophos-
phorus pesticides, their oxygen analog sulfones and sulfoxides, and aryl phosphate
industrial chemicals.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
230 C isothermal; if necessary, adjust temperature so that relative retention time
(rrt) to phosalone of coumaphos is about 1.56.
Carrier gas: helium; adjust flow rate so that phosalone elutes in about 8.5 min
(about 18 mL/min).
Injector temperature: 250 C
Detector
Flame photometric, phosphorus mode (FPD-P)
Detector Operating Conditions:
225-250 C
See Section 503 C for other information about FPD operation.
Set detector electronics (amplification, attenuation) so that response to 7.5 ng
phosalone is 50% full scale deflection (FSD).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–54
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
15
1
2
3
4
5
0
DG11
Chromatogram of: 1) 1.38 ng ethion, 2) 20.8 ng azinphos-methyl oxygen analog, 3) 7.28 ng phosalone,
4) 7.79 ng pyrazophos, and 5) 10.1 ng coumaphos at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–55
DG12 GLC, 100% METHYL SILOXANE, 230
C, ELCD-X
Applicability
Determinative step is applicable to residues of low volatility (late elution) and
containing halogen. It is particularly useful for residues such as halogenated pyre-
throids (cyfluthrin, alpha-cypermethrin).
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 100% methyl substituted
polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-linked. For
example, DB-1; see Table 502-a for equivalents. See Section 502 C, Recommended
Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
230 C isothermal; if necessary, adjust temperature so that relative retention time
(rrt) to phosalone of cis permethrin is about 1.55.
Carrier gas: helium or hydrogen; adjust flow rate so that phosalone elutes in about
8 min.
Injector temperature: 250 C
Detector
Electroconductivity, halogen mode (ELCD-X)
Detector Operating Conditions:
Base temperature 250 C; furnace temperature 900 C (or as specified in operat-
ing manual)
Reactor gas: hydrogen, flow as required by specific detector model; see operating
manual
See Section 503 D for other information about ELCD operation.
Set detector electronics (amplification, attenuation) so that response to 18 ng
phosalone is 50% full scale defection (FSD).
Other Considerations
Detector sensitivity can probably not be increased to match that of DG10, for the same
residues.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–56
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
DG12
Chromatogram of: 1) 8.72 ng ofurace, 2) 9.96 ng iprodione, 3) 17.86 ng phosalone,
4) 11.01 ng prochloraz, and 5) 21.06 ng alpha-cypermethrin at the conditions described.
510
min
15
1
2
3
4
5
0
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–57
DG13 GLC, 50% PHENYL, 50% METHYL SILOXANE,
200
C, EC
Applicability
Determinative step is applicable to residues containing halogen, sulfur, or other
electrophilic moieties. It is a general purpose system, but subject to interferences by
nonpesticides.
Column
Wide bore capillary, 30 m m · 0.53 mm id, coated with 50% phenyl, 50% methyl
substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-
linked. For example, DB-17; see Table 502-a for equivalents. See Section 502 C,
Recommedned Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of p,p'-DDT is 3.5 – 0.07 or rrt
c
of ethion is 3.36 – 0.07.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4 – 0.5 min
(about 20 mL/min).
Injector temperature: 250 C
Detector
Electron Capture (EC)
Detector Operating Conditions:
350 C
Make-up gas: nitrogen or argon/methane (95:5), at 30 mL/min
See Section 503 B for other information about EC detector operation.
Set detector electronics (amplification, attenuation) so that response to 0.15 ng
chlorpyrifos (on an amount within the detector’s linear range) is 50% full scale
deflection (FSD).
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column). Re-
sponse data in Appendix I are based on detector sensitivity of 50% FSD to 1.5 ng
chlorpyrifos.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–58
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
15
7
6
5
4
31
2
0
DG13
Chromatogram of: 1) 0.048 ng dicloran, 2) 0.049 ng heptachlor, 3) 0.15 ng chlorpyrifos, 4) 0.23 ng
endosulfan I, 5) 0.22 ng captan, 6) 0.24 ng endrin, and 7) 0.24 ng p,p￠ -DDT at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–59
DG14 GLC, 50% PHENYL, 50% METHYL SILOXANE,
200
C, FPD-P
Applicability
Determinative step is applicable to residues containing phosphorus. It is particularly
useful for residues such as organophosphate pesticides.
Column
Wide bore capillary, 30 mm · 0.53 mm id, coated with 50% phenyl, 50% methyl
substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-
linked. For example, DB-17; see Table 502-a for equivalents. See Section 502 C,
Recommended Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of ethion is 3.36 – 0.07.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4 – 0.5 min
(about 20 mL/min).
Injector temperature: 250 C
Detector
Flame photometric, phosphorus mode (FPD-P)
Detector Operating Conditions:
225-250 C
See Section 503 C for other information about FPD operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
A properly functioning system will give a response to 1.5 ng omethoate of ? 50%
FSD.
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–60
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
15
1
2
3
4
5
6
0
DG14
Chromatogram of: 1) 1.0 ng acephate, 2) 1.5 ng omethoate, 3) 1.0 ng monocrotophos,
4) 1.0 ng pirimiphos-methyl, 5) 1.0 ng chlorpyrifos, and 6) 3.0 ng ethion at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–61
DG15 GLC, 50% PHENYL, 50% METHYL SILOXANE,
230
C, FPD-S
Applicability
Determinative step is applicable to residues containing sulfur. It is particularly useful
for residues such as propargite, thiabendazole, and ethofumesate.
Column
Wide bore capillary, 30 m m · 0.53 mm id, coated with 50% phenyl, 50% methyl
substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-
linked. For example, DB-17; see Table 502-a for equivalents. See Section 502 C,
Recommended Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of ethion is 3.36 – 0.07.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4 – 0.5 min
(about 20 mL/min).
Injector temperature: 250 C
Detector
Flame photometric, sulfur mode (FPD-S)
Detector Operating Conditions:
225-250 C
See Section 503 C for other information about FPD operation.
Set detector electronics (amplification, attenuation) to produce greatest possible
response (50% full scale deflection [FSD]) to 15 ng chlorpyrifos is reasonable).
Other Considerations
Detector is not linear; quantitation of residues may be calculated from calibration
curve (response vs amount injected).
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–62
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
10 15
min
2520 30 35 4050
1
2
3
4
5
6
DG15
Chromatogram of: 1) 2.5 ng ethofumesate, 2) 5.0 ng endosulfan I, 3) 12.5 ng thiabendazole,
4) 10.0 ng endosulfan II, 5) 15.0 ng propargite, and 6) 15.0 ng endosulfan sulfate at the conditions
described. Using this system, 5.0 ng chlorpyrifos caused about 50% FSD response.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–63
DG16 GLC, 50% PHENYL, 50% METHYL SILOXANE,
200
C, ELCD-X
Applicability
Determinative step is applicable to residues containing halogen. It is particularly
useful for residues such as chlorinated hydrocarbon pesticides and polychlorinated
biphenyls.
Column
Wide bore capillary, 30 m m · 0.53 mm id, coated with 50% phenyl, 50% methyl
substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-
linked. For example, DB-17; see Table 502-a for equivalents. See Section 502 C,
Recommended Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of p,p￠-DDT is 3.5 – 0.07.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4 – 0.5 min
(about 20 mL/min).
Injector temperature: 250 C
Detector
Electroconductivity, halogen mode (ELCD-X)
Detector Operating Conditions:
Base temperature 250 C; furnace temperature 900 C (or as specified in operat-
ing manual)
Reactor gas: hydrogen, flow as required by specific detector model; see operating
manual
See Section 503 D for other information about ELCD operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–64
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
510
min
15
7
6
5
4
32
1
0
DG16
Chromatogram of: 1) 0.85 ng dicloran, 2) 0.58 ng heptachlor, 3) 1.65 ng chlorpyrifos, 4) 1.01 ng
endosulfan I, 5) 4.58 ng captan, 6) 1.56 ng endrin, and 7) 3.56 ng p,p’-DDT at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–65
DG17 GLC, 50% PHENYL, 50% METHYL SILOXANE,
200
C, N/P
Applicability
Determinative step is applicable to residues containing nitrogen. It is particularly
useful for residues such as triazines, triazoles, and THPI (captan metabolite).
Column
Wide bore capillary, 30 m m · 0.53 mm id, coated with 50% phenyl, 50% methyl
substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and cross-
linked. For example, DB-17; see Table 502-a for equivalents. See Section 502 C,
Recommended Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of ethion is 3.36 – 0.07.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 4 – 0.5 min
(about 20 mL/min).
Injector temperature: 250 C
Detector
Alkali bead detector, nitrogen selective (N/P)
Detector Operating Conditions:
250 C
3.7 – 0.1 mL/min hydrogen and 110 mL/min air
See Section 503 E for other information about N/P detector operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
A properly functioning system will give a response to 1.5 ng omethoate of ? 50%
FSD.
Other Considerations
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–66
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
min
5100 15
1
2
3
4
5
DG17
Chromatogram of: 1) 1.5 ng atrazine, 2) 1.5 ng chlorpyrifos, 3) 15.0 ng carbaryl, 4) 10.0 ng imazalil, and
5) 5.0 ng procyazine at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–67
DG18 GLC, 50% CYANOPROPYLPHENYL, 50% METHYL
SILOXANE, 200
C, EC
Applicability
Determinative step is applicable to residues containing halogen, sulfur, or other
electrophilic moieties. It is a general purpose system, subject to interferences from
nonpesticides; it is particularly useful for separating BHC isomers and hexachloro-
benzene.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 50% cyanopropylphenyl, 50%
methyl substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and
cross-linked. For example, DB-225; see Table 502-a for equivalents. See Section 502
C, Recommended Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of lindane is 0.69 – 0.02 and p,p￠-DDT is 3.6 – 0.06 or rrt
c
of
ethion is 3.9 – 0.1.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 5.5 – 0.5
min (about 20 mL/min).
Injector temperature: 250 C
Detector
Electron Capture (EC)
Detector Operating Conditions:
350 C
Make-up gas: nitrogen or argon/methane (95:5), a 30 mL/min
See Section 503 B for other information about EC detector operation.
Set detector electronics (amplification, attenuation) so that response to 0.15 ng
chlorpyrifos (on an amount within the detector’s linear range) is 50% full scale
deflection (FSD).
Other Considerations
Columns containing cyano moieties in the phase must not be connected to nitrogen
selective or electrolytic conductivity detectors, so this column cannot be used with a
different detector to confirm residues tentatively identified using this
system.
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column). Re-
sponse data in Appendix I are based on detector sensitivity of 50% FSD to 1.5 ng
chlorpyrifos.
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–68
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
5
min
20
7
6
5
4
3
2
1
10 150
DG18
Chromatogram of: 1) 0.032 ng hexachlorobenzene, 2) 0.049 ng a -BHC, 3) 0.056 lindane, 4) 0.15 ng
chlorpyrifos, 5) 0.054 ng b -BHC, 6) 0.054 ng d -BHC, and 7) 0.201 ng p,p￠ -DDT at the conditions described.
SECTION 302Pesticide Analytical Manual Vol. I
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
302–69
DG19 GLC, 50% CYANOPROPYLPHENYL, 50% METHYL
SILOXANE, 200
C, FPD-P
Applicability
Determinative step is applicable to residues containing phosphorus. It is particularly
useful for residues such as organophosphate pesticides.
Column
Wide bore capillary, 30 m · 0.53 mm id, coated with 50% cyanopropylphenyl, 50%
methyl substituted polysiloxane liquid phase, 1-1.5 m m film thickness, bonded and
cross-linked. For example, DB-225; see Table 502-a for equivalents. See Section 502
C, Recommended Operating Procedure for Wide Bore Columns.
Column Operating Conditions:
200 C, isothermal; if necessary, adjust temperature so that relative retention time
to chlorpyrifos (rrt
c
) of ethion is 3.9 – 0.1.
Carrier gas: helium; adjust flow rate so that chlorpyrifos elutes in about 5.5 – 0.5
min (about 20 mL/min).
Injector temperature: 250 C
Detector
Flame photometric, phosphorus mode (FPD-P)
Detector Operating Conditions:
225-250 C
See Section 503 C for other information about FPD operation.
Set detector electronics (amplification, attenuation) so that response to 1.5 ng
chlorpyrifos is 50% full scale deflection (FSD).
Other Considerations
Columns containing cyano moieties in the phase must not be connected to nitrogen
selective or electrolytic conductivity detectors, so this column cannot be used with a
different detector to confirm residues tentatively identified using this
system.
Rrt
c
s and ng required to cause 50% FSD response are listed in Appendix I, PESTDATA
(many data in PESTDATA were collected using equivalent packed column).
Example chromatogram is on next page.
Pesticide Analytical Manual Vol. ISECTION 302
302–70
Transmittal No. 2000-1 (10/1999)
Form FDA 2905a (6/92)
5
min
10
5
4
3
2
1
0
DG19
Chromatogram of: 1) 0.5 ng methamidophos, 2) 1.0 ng diazinon, 3) 1.0 ng acephate,
4) 1.5 ng chlorpyrifos, and 5) 1.0 ng monocrotophos at the conditions described.
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–1
303: METHOD II FOR NONFATTY FOODS
BASIC REFERENCE
Mills, P.A., et al. (1963) J. Assoc. Off. Agric. Chem. 46, 186-191
GENERAL PRINCIPLES
Residues are extracted by blending with acetonitrile or water and acetonitrile, then
transferred into petroleum ether by liquid-liquid partitioning. Subsequent cleanup of
the extract with Florisil column chromatography results in an extract suitable for deter-
mination by GLC; two elution systems produce different elution patterns, useful in con-
firmatory or additional analyses.
The amount of sample represented in the final solution is calculated from the aliquot of
acetonitrile extract used and the proportion of petroleum ether retrieved from the par-
titioning step; this calculation is valid only when the original filtered extract is homoge-
neous. Variations in the extraction step are used for products of high (>5%) sugar con-
tent to ensure homogeneity.
APPLICABILITY
Consult Guide to PAM I for additional information pertinent to the appropriate appli-
cation of multiresidue methodology.
Method is generally applicable to relatively nonpolar residues in nonfatty commodities,
i.e., fruits and vegetables containing ￡ 2 g fat in 100 g sample. Extraction E1 is applicable
to products with high moisture (>75%) content; that extraction is also applicable to
eggs if sample size is reduced (Extraction E2). Extraction E3 is applicable to dry prod-
ucts (<75% water), E4 to products with 5-15% sugar, and E5 to products with >15%
sugar. See Section 201 for percentages fat, water, and sugar of many commodities. Florisil
cleanup step prevents applicability to very polar residues. See Table 303-a, following the
method description, for results of recovery tests.
METHOD MODULES
Choose from these method modules, using Figure 303-a for guidance:
Extraction (E) Recommended Use
E1 (p. 303-7) Extraction with acetonitrile, partition fruits and vegetables
into petroleum ether with high moisture (>75%), and low sugar
(<5%), low fat (<2%)
E2 (p. 303-8) Extraction from eggs with acetonitrile, whole eggs
partition into petroleum ether
E3 (p. 303-9) Extraction with water/acetonitrile, dried egg whites,
partition into petroleum ether grains, and other foods with
low moisture (<75%),
low fat (<2%)
E4 (p. 303-9) Extraction with acetonitrile and water, fruits and other foods
partition into petroleum ether with high sugar (5-15%)
E5 (p. 303-10) Extraction with heated acetonitrile fruits and other foods
and water, partition into petroleum with very high sugar
ether (>15%)
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–2
Cleanup (C)
C1 (p. 303-13) Florisil column cleanup, with three for relatively nonpolar
ethyl ether/petroleum ether eluants residues
C2 (p. 303-14) Florisil column cleanup, with three alternative to C1, some
methylene chloride eluants additional residues re-
covered
Determination (D)
(See Section 302 for full details of GLC modules.)
DG 1 (p. 302-33) GLC, 100% methyl siloxane column, residues with halogen,
200 , EC detector sulfur, other moieties
DG 2 (p. 302-35) GLC, 100% methyl siloxane column, residues with
200 , FPD-P phosphorus
DG 3 (p. 302-37) GLC, 100% methyl siloxane column, residues with halogen
200 , ELCD-X
DG 4 (p. 302-39) GLC, 100% methyl siloxane column, residues with nitrogen
200 , ELCD-N
DG 5 (p. 302-41) GLC, 100% methyl siloxane column, residues with nitrogen
200 , N/P detector or phosphorus
DG 7 (p. 302-45) GLC, 100% methyl siloxane column, early eluting residues
130 , EC detector with halogen, sulfur,
other moieties
DG10 (p. 302-51) GLC, 100% methyl siloxane column, late eluting residues
230 , EC detector with halogen, sulfur,
other moieties
DG12 (p. 302-55) GLC, 100% methyl siloxane column, late eluting residues with
230 , ELCD-X halogen
DG13 (p. 302-57) GLC, 50% phenyl, 50% methyl residues with halogen,
siloxane column, 200 , EC detector sulfur, other moieties
DG14 (p. 302-59) GLC, 50% phenyl, 50% methyl residues with
siloxane column, 200 , FPD-P phosphorus
DG16 (p. 302-63) GLC, 50% phenyl, 50% methyl residues with halogen
siloxane column, 200 , ELCD-X
DG17 (p. 302-65) GLC, 50% phenyl, 50% methyl residues with nitrogen or
siloxane column, 200 , N/P detector phosphorus
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–3
VALIDATION
Many combinations of method modules are possible. The following combinations have
undergone interlaboratory validation and are recommended for use:
E1 + C1 + DG1
Validation reports:
Krause, R.T. (1966) J. Assoc. Off. Anal. Chem. 49, 460-463. Collaborative study
leading to AOAC official final action status for aldrin, DDE, and methoxychlor
in potatoes.
Figure 303-a
Recommended Approach: Nonfatty Foods
>75% water
<5% sugars
E1
whole
eggs
E2
<75%
water
E3
>75% water
5-15% sugars
E4
>75% water
>15% sugars
E5
C1/C2
DG3/16
and
DG12
residues
with
halogen
DG4/5/17
residues with
nitrogen
DG1/13
and
DG7
and
DG10
residues with
electron
capturing
moieties
DG2/14
residues
with
phosphorus
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–4
Gaul, J. (1966) J. Assoc. Off. Anal. Chem. 49, 463-467. Collaborative study
leading to AOAC official final action status for lindane, heptachlor, and
TDE in endive and cauliflower.
Davidson, A.W. (1966) J. Assoc. Off. Anal. Chem. 49, 468-472. Collaborative study
leading to AOAC official final action status for BHC, p,p’-DDT, and endrin on
apricots and strawberries.
Wells, C. (1967) J. Assoc. Off. Anal. Chem. 50, 1205-1215. Interlaboratory study
supporting validity of method for 32 residues in five groups of nonfatty commodi-
ties; studies supported extension of official status for previously collaborated resi
dues in 13 additional commodities.
Burke, J.A. (1968) J. Assoc. Off. Anal. Chem. 51, 311-314. Interlaboratory study
supporting validity of method for nine residues in 21 nonfatty foods; studies
supported extension of official status for previously collaborated residues to
15 additional commodities.
Krause, R.T. (1973) J. Assoc. Off. Anal. Chem. 56, 721-727. Collaborative study
leading to AOAC official final action status for dieldrin, heptachlor epoxide,
mirex, and Perthane in apples and cauliflower.
E1 + C1 + (predecessor to) DG5
Validation reports:
Wessel, J.R. (1967) J. Assoc. Off. Anal. Chem. 50, 430-439. Collaborative study lead
ing to AOAC official final action status for diazinon, ethion, malathion, parathion,
parathion-methyl, and ronnel in lettuce and apples.
Finsterwalder, C. W. (1976) J. Assoc. Off. Anal. Chem. 59, 169-171. Collaborative
study leading to AOAC official final action status for parathion in kale.
Wells, C. (1967) J. Assoc. Off. Anal. Chem. 50, 1205-1215. Interlaboratory study
supporting validity of method for 32 residues in five groups of nonfatty commodi-
ties; studies were later referenced (Burke, J.A. (1971) J. Assoc. Off. Anal. Chem. 54,
325-327) as support for extension of official status for diazinon, ethion, malathion,
parathion, parathion-methyl, and ronnel in barley, broccoli, cabbage, carrots,
cauliflower, cucumbers, grapes, green peppers, mustard greens, oats, potatoes,
squash, tomatoes, turnips, turnip greens, and wheat.
E2 + C1 + DG1
Validation report:
Finsterwalder, C. W. (1976) J. Assoc. Off. Anal. Chem. 59, 169-171. Collaborative
study leading to AOAC official final action status for o,p’-DDT, p,p’-DDT, and
p,p’-DDE in kale and p,p’-DDE, dieldrin, lindane, and heptachlor epoxide in
eggs.
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–5
E3 + C1 + DG1
Validation reports:
Burke, J.A. (1971) J. Assoc. Off. Anal. Chem. 54, 325-327. Referenced the follow
ing publications in a recommendation to extend official status to extraction step
E3 (for low moisture commodities) for previously collaborated residues on bar-
ley, corn meal, hay, oats, popcorn, and wheat:
Bertuzzi, P., et al. (1967) J. Assoc. Off. Anal. Chem. 50, 623-627
Wilderman, M., and Shuman, H., (1968) J. Assoc. Off. Anal. Chem.
51, 892-895
Burke, J.A., et al. (1971) J. Assoc. Off. Anal. Chem. 54, 142-146. Evalua-
tion of two extraction procedures.
E4 + C1 + DG1 and E5 + C1 + DG1
Validation report:
Burke, J.A. (1970) J. Assoc. Off. Anal. Chem. 53, 355-357. Referenced the follow-
ing publication in a recommendation to extend official status to extraction steps
E4 and E5 (for commodities with high sugar) for previously collaborated residu-
dues:
Porter, M.L., and Burke, J.A. (1969) J. Assoc. Off. Anal. Chem. 52, 1280-1283.
Description of way to accommodate commodities with high sugar.
For all combinations above, AOAC official method reference: Official Methods of Analysis
of the AOAC (1990) 15th ed., 970.52 A, B, E, H, I, J, K, O, and R.
E1 + C2 + DG1
Validation reports:
Mitchell, L.E. (1976) J. Assoc. Off. Anal. Chem. 59, 209-212. Collaborative study
leading to AOAC official final action status for endosulfan, endosulfan sulfate,
tetradifon, and tetrasul in apples and cucumbers.
McMahon, B.M. (1988) J. Assoc. Off. Anal. Chem. 71, 94-97. Presentation of ad-
ditional validation data for previously collaborated residues to 29 additional com-
modities.
AOAC official method reference: Official Methods of Analysis of the AOAC (1990) 15th ed.,
976.23.
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–6
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–7
E1 EXTRACTION WITH ACETONITRILE, PARTITION INTO PETROLEUM
ETHER
References
Mills, P.A., et al. (1963) J. Assoc. Off. Agric. Chem. 46, 186-191
Porter, M., et al. (1967) J. Assoc. Off. Anal. Chem. 50, 644-645
Principles
Residues are extracted from high moisture products by a single blending with acetoni-
trile, a solvent miscible with the water in high moisture products and also capable of
dissolving organic residues. An aliquot of filtered extract is diluted with water and resi-
dues are transferred into petroleum ether by liquid-liquid partitioning; transfer to hy-
drocarbon solvent and removal of all traces of polar acetonitrile permit subsequent
cleanup on Florisil. Amount of sample represented in final solution is calculated from
aliquot of acetonitrile extract used and proportion of petroleum ether retrieved from
partitioning step.
Apparatus
blender, high speed; explosion-proof Waring Blendor, 1 qt jar
Büchner funnel (Büchner), porcelain, 12 cm diameter
filter paper, Shark Skin
?
, to fit Büchner
graduated cylinders (graduates), glass-stoppered (g-s), 100 mL, and plain,
250 mL
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, gradu-
ated or plain receiving flask
separatory funnel (separator), 1 L
vacuum filtration flask, 500 mL
Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distilla-
tion directions
boiling chips, 20-30 mesh carborundum
petroleum ether, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Chop or blend representative sample. Weigh 100 g sample into
blender jar and add 200 mL acetonitrile (10 g Celite may be added as
filter aid).
? Blend 2 min at high speed and filter with suction through Büchner
fitted with filter paper into vacuum filtration flask.
? Transfer filtrate to 250 mL graduate and record volume (F).
? Transfer measured volume of filtrate to 1 L separator.
? Carefully measure 100 mL petroleum ether in same graduate used to
measure filtered extract and pour into separator containing extract.
Shake vigorously 1-2 min.
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–8
? Add 10 mL saturated sodium chloride solution and 600 mL water. Hold
separator in horizontal position and mix vigorously 30-45 sec. (Inad-
equate mixing may lead to low recoveries of some pesticides, e.g., BHC,
TDE.)
? Let layers separate, discard aqueous layer, and gently wash solvent layer
with two 100 mL portions water. Discard washings, transfer solvent layer
to 100 mL g-s graduate, and record volume (P).
? Add about 15 g sodium sulfate to graduate, stopper, and shake vigor
ously. Do not let extract remain with sodium sulfate >1 hr or losses of or-
ganochlorine pesticides by adsorption may result.
? Transfer solution directly to Florisil column, C1 or C2, or concentrate to
5-10 mL in K-D for transfer.
? Calculate weight sample placed on Florisil column as:
g = S · ·
F
T
P
100
where:
S = g sample extracted
F = volume of filtered acetonitrile extract
T = total volume (mL water in sample + mL acetonitrile added –
correction in mL for volume contraction). 5 mL contraction
volume is used for 80-95 mL water + 200 mL acetonitrile.
P = mL petroleum ether extract recovered
100 = mL petroleum ether into which residues were partitioned.
See Section 201 for percentage water in commodity; 85% may be
assumed for most fruits and vegetables.
ALTERNATIVES:
E2 EXTRACTION FROM EGGS WITH ACETONITRILE, PARTITION
INTO PETROLEUM ETHER
Additional Reference
Wessel, J.R. (1969) J. Assoc. Off. Anal. Chem. 52, 172-175
Directions
? Blend combined yolks and whites of whole eggs at low speed at least 5
min or until sample is homogeneous. Low speed blending will minimize
foaming or whipping of sample.
? Weigh ￡ 25g thoroughly mixed yolks and whites into blender jar and add
200 mL acetonitrile.
? Proceed as in E1, “Blend 2 min at high speed... .”
? Calculate g sample to be placed on Florisil column as in E1, except:
T = 215 (15 mL water in 25 g whole eggs + 200 mL acetonitrile;
contraction volume is negligible).
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–9
E3 EXTRACTION WITH 35% WATER/ACETONITRILE, PARTITION INTO
PETROLEUM ETHER
Additional Reference
Bertuzzi, P.A., et al. (1967) J. Assoc. Off. Anal. Chem. 50, 623-627
Principles
Residues are extracted from nonfatty, low moisture products by blending with
35% water/acetonitrile. Water in extractant is needed to obtain adequate extrac-
tion of residues from low moisture products. Aliquot (￡ 250 mL) of filtered extract
is diluted with water and residues are transferred into petroleum ether by liquid-
liquid partitioning; transfer to hydrocarbon solvent and removal of all traces of
polar acetonitrile permit subsequent cleanup on Florisil. Water:acetonitrile
dilution ratio of 4:1 is used for transfer of residues to petroleum ether; restricting
volume of filtered extract to ￡ 250 mL allows extract, adequate water for dilution,
and 100 mL petroleum ether to fit in 1 L separator.
Directions
? Grind sample to pass 20 mesh sieve.
? Weigh 20-25 g sample into blender jar, and add 350 mL 35% water/
acetonitrile(10 g Celite may be added as filter aid). If larger sample is
required, add sufficient additional extraction mixture to wet sample
and permit thorough blending.
? Blend 5 min at high speed and filter with suction through Büchner
fitted with filter paper into vacuum filtration flask.
? Take ￡ 250 mL filtered extract for analysis. Record volume (F).
? Continue as in E1, “Transfer measured volume of filtrate to 1 L
separator…”
? Calculate g sample to be placed on Florisil column as in E1, except:
T = mL water in sample + mL 35% water/acetonitrile. No correction
for volume contraction is needed. If water content of sample is
<10%, disregard it and use T = volume extracting mixture.
E4 EXTRACTION WITH ACETONITRILE AND WATER, PARTITION INTO
PETROLEUM ETHER
Additional Reference
Porter, M.L., and Burke, J.A. (1969) J. Assoc. Off. Anal. Chem. 52, 1280-1283
Principles
Residues are extracted from nonfatty, high moisture commodities that contain 5-
15% sugar by addition of water and subsequent blending with acetonitrile. Water
is added to the product to dilute the effect of sugar, which can cause separation
of water and acetonitrile phases in the filtered extract and thus disrupt homoge-
neity of the extract solution. Aliquot (￡ 250 mL) of filtered extract is diluted with
water and residues are transferred into petroleum ether by liquid-liquid partition-
ing; transfer to hydrocarbon solvent and removal of all traces of polar acetonitrile
permit subsequent cleanup on Florisil.
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–10
Directions
? Weigh 100 g sample into blender jar and add 200 mL acetonitrile and 50
mL water.
? Blend 2 min at high speed and filter with suction through Büchner fitted
with filter paper into vacuum filtration flask.
? Transfer ￡ 250 mL filtered extract to 250 mL graduate. Record volume
(F).
? Continue as in E1, “Transfer measured volume to 1 L separator.”
? Calculate g sample to be placed on Florisil column as in E1, except:
T = mL water in sample + mL acetonitrile added + mL water added –
correction in mL for volume contraction. When 50 mL water is
added, T is 325 for foods of 85% water content. Contraction
volumeof 5 mL is used for 80-95 mL water + 200 mL acetonitrile.
E5 EXTRACTION WITH HEATED ACETONITRILE AND WATER,
PARTITION INTO PETROLEUM ETHER
Additional Reference
Porter, M.L., and Burke, J.A. (1969) J. Assoc. Off. Anal. Chem. 52, 1280-1283
Principles
Residues are extracted from commodities with >15% sugar using a heated mixture
of water and acetonitrile. Unheated water and acetonitrile (as in E4) is insufficient
to prevent separation of water and acetonitrile phases in the filtered extract when
sugar is >15%. Aliquot (￡ 250 mL) of filtered extract is diluted with water and
residues are transferred into petroleum ether by liquid-liquid partitioning; trans-
fer to hydrocarbon solvent and removal of all traces of polar acetonitrile permit
subsequent cleanup on Florisil.
Directions
? Weigh 100 g sample into blender jar and add heated (75 C) mixture of
200 mL acetonitrile and 50 mL water.
? To analyze raisins, weigh 50 g. Heat 50 mL water and 200 mL acetonitrile
separately to 75 C. Add 40-50 mL hot water to container in which raisins
were weighed and stir or shake to disperse in water. Transfer to blender
jar, using remaining water to rinse container into blender jar. Rinse
container with hot acetonitrile and add to blender jar; add remaining
hot acetonitrile to blender jar.
? Blend 2 min at high speed and filter with suction through Büchner fitted
with filter paper into vacuum filtration flask.
? Before filtered extract cools, transfer ￡ 250 mL to 250 mL graduate.
Record volume (F).
? Continue as in E1, “Transfer measured volume of filtrate to 1 L
separator…”
? Calculate g sample to be placed on Florisil column as in E1, except:
T = mL water in sample + mL acetonitrile added + mL water added –
correction in mL for volume contraction. When 50 mL water
added, T is 325 for foods of 85% water content. Contraction volume
of 5 mL is used for 80-95 mL water + 200 mL acetonitrile.
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–11
C1 FLORISIL COLUMN CLEANUP, WITH THREE ETHYL ETHER/
PETROLEUM ETHER ELUANTS
Reference
Mills, P.A., et al. (1963) J. Assoc. Off. Agric. Chem. 46, 186-191
Principles
Residues in solution are separated from sample co-extractives on a column of
Florisil adsorbent; eluants of increasing polarity sequentially remove residues
from the column.
Apparatus
chromatographic column, 22 mm id ￥ 300 mm, Teflon stopcock, coarse
porosity fritted disc
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-
ball micro-Snyder column, volumetric or graduated receiving flask
Reagents
boiling chips, 20-30 mesh carborundum
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preserva-
tive; see Section 204 for peroxide test
Florisil, PR Grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
petroleum ether, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
eluants: 6% (v/v) ethyl ether/petroleum ether
15% (v/v) ethyl ether/petroleum ether
50% (v/v) ethyl ether/petroleum ether
Directions
? Place activated Florisil (4" or weight determined by lauric acid value)
in 22 mm id column; add about 0.5" sodium sulfate. Prewet column
with 40-50 mL petroleum ether. Place K-D with volumetric or gradu-
ated receiving flask under column to receive eluate.
? Transfer sample extract solution to column, letting it pass through at
about 5 mL/min. Rinse container (and sodium sulfate if present) with
two 5 mL portions petroleum ether, transfer rinsings to column, and
rinse walls of chromatographic tube with additional small portions
petroleum ether.
? Elute column at about 5 mL/min with 200 mL 6% ethyl ether/
petroleum ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 15% ethyl
ether/petroleum ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 50% ethyl
ether/petroleum ether eluant.
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–12
? Add boiling chips to K-Ds and concentrate each eluate to suitable
definite volume. When volume <5 mL is needed, use two-ball micro-
Snyder or micro-Vigreaux column during final evaporation in receiving
flask.
? Use appropriate determinative steps, such as DG1 or DG13, DG7, and
DG10, to identify and measure residues.
ALTERNATIVE:
C2 FLORISIL COLUMN CLEANUP, WITH THREE METHYLENE
CHLORIDE ELUANTS
Additional Reference
Mills, P.A., et al. (1972) J. Assoc. Off. Anal. Chem. 55, 39-43
Additional Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distillation
directions
hexane, distilled from all-glass apparatus
methylene chloride, distilled from all-glass apparatus
eluants: 1—20% methylene chloride/hexane (v/v). Dilute 200 mL
methylene chloride with hexane. Allow mixture to reach room
temperature, and adjust volume to 1 L with hexane.
2—50% methylene chloride/0.35% acetonitrile/49.65%
hexane (v/v/v). Pipet 3.5 mL acetonitrile into 500 mL
methylene chloride and dilute with hexane. Allow mixture to
reach room temperature and adjust to 1 L with hexane.
3—50% methylene chloride/1.5% acetonitrile/48.5% hexane
(v/v/v). Pipet 15 mL acetonitrile into 500 mL methylene
chloride and dilute with hexane. Allow mixture to reach room
temperature and adjust to 1 L with hexane.
Directions
? Prepare Florisil column as in C1. Place K-D with volumetric or graduated
receiving flask under column to receive eluate.
? Transfer sample extract solution to column, letting it pass through at
about 5 mL/min. Rinse container (and sodium sulfate if present) with
two 5 mL portions hexane, transfer rinsings to column, and rinse walls
of chromatographic tube with additional small portions hexane.
? Elute column at about 5 mL/min with 200 mL eluant 1.
? Change K-Ds and elute with 200 mL eluant 2.
? Change K-Ds and elute with 200 mL eluant 3.
? Add boiling chips to K-Ds and concentrate each eluate to suitable
definite volume. When volume <5 mL is needed, use two-ball micro-
Snyder or micro-Vigreaux column during evaporation.
? Use appropriate determinative steps to identify and measure residues.
Pesticide Analytical Manual Vol. I
SECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–13
DETERMINATION
Inject concentrated extract equivalent to 20 mg (whole product) into the follow-
ing GLC systems (Section 302)for determination of residues.
Minimum recommended determinations:
DG1 or DG13 residues with halogen, sulfur, or other moieties
or
DG3 or DG16 organohalogen residues
DG10 late eluting residues, especially pyrethroids
DG12 late eluting organohalogen residues, especially pyrethroids
DG7 early eluting residues with halogen, sulfur, or other moietites
DG2 or DG14 organophosphorus residues; large amounts of sulfur may
interfere
DG4 organonitrogen residues; selective to nitrogen, but
coextractives may contain nitrogen
DG5 or DG17 organonitrogen and organophosphorus residues
For accurate quantitation, reference standards should be dissolved in same
solvent as concentrated extract, only peaks >10% FSD should be measured, and
peak sizes of residue and reference standard should match within – 25%.
See Chapter 5 for additional information about operation of GLC systems; Section
504 provides information about quantitation of residues.
See Section 205 for additional information about reference standards.
See Section 104 for additional information about reporting residues and deter-
mining compliance with regulations.
See Section 105 for additional information about analytical limits of quantitation.
CONFIRMATION
After residues have been tentatively identified and quantitated by comparison to
appropriate reference standards, confirm identity according to principles dis-
cussed in Section 103. Use appropriate tables of data (PESTDATA, tables accom-
panying each method, Index to Methods) to choose most appropriate determina-
tive steps and/or alternative methods for confirmation.
Pesticide Analytical Manual Vol. ISECTION 303
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
303–14
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–1
Pesticide Analytical Manual Vol. I SECTION 304
304: METHOD FOR FATTY FOODS
BASIC REFERENCE
Mills, P.A. (1959) J. Assoc. Off. Agric. Chem. 42, 734-740
GENERAL PRINCIPLES
Fat and residues are extracted from fatty foods and dissolved in an organic solvent.
Residues are separated from the extracted fat to produce a cleaned up extract solution
suitable for determination by gas chromatography.
APPLICABILITY
Consult Guide to PAM I for additional information pertinent to the appropriate
application of multiresidue methodology.
Method is applicable to moderately nonpolar residues in fatty foods. Residue polarity
will affect recovery in Cleanups 1 and 2; neither very nonpolar nor very polar residues
are recovered completely. See Table 304-a, following the method description, for
results of recovery tests.
METHOD MODULES
Choose from these method modules, using Figure 304-a for guidance:
Extraction (E) Recommended Use
E1 (p. 304-5) Extraction of fat with sodium sulfate, animal tissues, fatty fish
petroleum ether
E2 (p. 304-7) Small scale extraction of fat with animal tissues, fatty fish
sodium sulfate, petroleum ether
E3 (p. 304-9) Extraction of fat by filtering butter, oils
E4 (p. 304-11) Extraction of fat with solvents from cheese, milk, egg yolks,
denatured product dried whole eggs
E5 (p. 304-13) Extraction of fat with solvents oilseeds, high fat feeds or
feed materials, grains, nuts
Cleanup (C)
C1 (p. 304-15) Acetonitrile-petroleum ether for relatively few samples
partitioning, Florisil column cleanup,
three mixed ether eluants
C2 (p. 304-17) Acetonitrile-petroleum ether for better cleanup than
partitioning, Florisil column cleanup, C1
three methylene chloride eluants
C3 (p. 304-18) Acetonitrile-petroleum ether to separate PCBs from
partitioning, Florisil column cleanup, most pesticides
petroleum ether and three mixed
ether eluants
C4 (p. 304-19) Acetonitrile-petroleum ether to separate PCBs from
partitioning, Florisil column cleanup, most pesticides
petroleum ether and three methylene
chloride eluants
C5 (p. 304-21) Gel permeation chromatography for efficient analysis
(GPC) of many samples (can
be automated)
Pesticide Analytical Manual Vol. ISECTION 304
304–2
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
C6 (p. 304-24) GPC, Florisil column (4 g) cleanup, when C5 provides in-
three methylene chloride eluants sufficient cleanup
C7 (p. 304-27) Florisil column (4 g) cleanup, two to decrease time, sol-
mixed ether eluants, optional alkaline vent use compared to
hydrolysis C1
C8 (p. 304-29) Dispersion on alumina, Florisil to reduce time com-
column cleanup, three mixed ether pared to C1; screen-
eluants ing test only
C9 (p. 304-31) Dispersion on alumina, Florisil to reduce time com-
columncleanup, three methylene pared to C3; screen-
chloride eluants ing test only
Determinations (D)
(See Section 302 for full details of GLC modules.)
DG 1 (p. 302-33) GLC, 100% methyl siloxane column, residues with halogen,
200 , EC detector sulfur, other moieties
DG 2 (p. 302-35) GLC, 100% methyl siloxane column, residues with
200 , FPD-P phosphorus
DG 3 (p. 302-37) GLC, 100% methyl siloxane column, residues with halogen
200 , ELCD-X
DG 4 (p. 302-39) GLC, 100% methyl siloxane column, residues with nitrogen
200 , ELCD-N
DG 5 (p. 302-41) GLC, 100% methyl siloxane column, residues with nitrogen
200 , N/P or phosphorus
DG 7 (p. 302-45) GLC, 100% methyl siloxane column, early eluting residues
130 , EC detector with halogen, sulfur,
other moieties
DG10 (p. 302-51) GLC, 100% methyl siloxane column, late eluting residues
230 , EC detector with halogen, sulfur,
other moieties
DG12 (p. 302-55) GLC, 100% methyl siloxane column, late eluting residues
230 , ELCD-X with halogen
DG13 (p. 302-57) GLC, 50% phenyl, 50% methyl residues with halogen,
siloxane column, 200 , EC detector sulfur, other moieties
DG14 (p. 302-59) GLC, 50% phenyl, 50% methyl residues with
siloxane column, 200 , FPD-P phosphorus
DG16 (p. 302-63) GLC, 50% phenyl, 50% methyl residues with halogen
siloxane column, 200 , ELCD-X
DG17 (p. 302-65) GLC, 50% phenyl, 50% methyl residues with nitrogen
siloxane column, 200 , N/P detector or phosphorus
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–3
Pesticide Analytical Manual Vol. I SECTION 304
VALIDATION
Many combinations of the method modules are possible. The following combinations
have undergone interlaboratory validation and are recommended for use:
E1 + C1 + DG1
Validation reports:
Carr, R.L. (1971) J. Assoc. Off. Anal. Chem. 54, 525-527. Collaborative study
leading to AOAC official final action status for a-BHC, p,p￠-DDE, p,p￠-TDE,
p,p'-DDT, dieldrin, and heptachlor epoxide in fish.
Sawyer, L.D. (1973) J. Assoc. Off. Anal. Chem. 56, 1015-1023. AOAC collaborative study
leading to AOAC official final action status for polychlorinated biphenyls in poultry
fat and fish.
AOAC official method reference: Official Methods of Analysis of the AOAC (1990)15th
ed., 970.52, A, B, E, H, I, J, L, N, O, and R.
Figure 304-a
Recommended Approach: Fatty Foods
animal
tissues,
fatty fish
E1 or E2
butter, oils
E3
dairy, egg
yolks, whole
dried eggs
E4
C1/C2/C6
oilseeds,
high fat feeds,
grains, nuts
E5
C7C3/C4
DG3/16
and
DG12
residues
with
halogen
DG4/5/17
residues with
nitrogen
DG1/13
and
DG7
and
DG10
residues
with
electron
capturing
moieties
DG2/14
residues
with
phosphorus
Pesticide Analytical Manual Vol. ISECTION 304
304–4
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
E2 + C7 + DG1
Validation report:
Erney, D. R. (1983) J. Assoc. Off. Anal. Chem. 66, 969-973. Collaborative study
leading to AOAC official final action status for p,p'-DDE, p,p'-DDT, p,p'-TDE,
dieldrin, heptachlor epoxide, and polychlorinated biphenyls in fish.
AOAC official method reference: Official Methods of Analysis of the AOAC (1990) 15th
ed., 983.21.
E4 + C1 + DG1
Validation reports:
Johnson, L. (1965) J. Assoc. Off. Agric. Chem. 48, 668-675. Collaborative study
leading to AOAC official final action status for dieldrin and heptachlor epoxide
in dairy products.
Carr, R.L. (1970) J. Assoc. Off. Anal. Chem. 53, 152-154. Collaborative study
leading to AOAC official final action status for BHC, p,p'-DDE, p,p'-TDE,
o,p'-DDT, p,p'-DDT, lindane, and methoxychlor in dairy products.
Krause, R.T. (1973) J. Assoc. Off. Anal. Chem. 56, 721-727. Collaborative study
leading to AOAC official final action status for Perthane in dairy products.
Sawyer, L.D. (1978) J. Assoc. Off. Anal. Chem. 61, 282-291. Collaborative study
leading to AOAC official final action status for polychlorinated biphenyls in dairy
products.
AOAC official method reference: Official Methods of Analysis of the AOAC (1990) 15th
ed., 970.52, A, B, E, H, I, J, L, N, O, and R.
E3 + C1 + DG1
Validation report:
Wells, C. (1967) J. Assoc. Off. Anal. Chem. 50, 1205-1215. Validation study leading
to AOAC official final action status for dieldrin and heptachlor epoxide in
vegetable oils.
AOAC official method reference: Official Methods of Analysis of the AOAC (1990) 15th
ed., 970.52 A, B, E, H, I, J, L, N, O, and R.
E1 + C6 + DG1 and E3 + C6 + DG1
Validation report:
Griffitt, K.R., et al. (July 1983) “Miniaturized Florisil Column Cleanup of Chlori-
nated and Organophosphate Eluates in Total Diet Samples,” LIB 2722, FDA,
Rockville, MD.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–5
Pesticide Analytical Manual Vol. I SECTION 304
E1 EXTRACTION OF FAT WITH SODIUM SULFATE, PETROLEUM ETHER
Reference
Porter, M.L., et al. (1970) J. Assoc. Off. Anal. Chem. 53, 1300-1303
Principles
Fat and residues are removed from fish and animal tissue by dissolving them in
petroleum ether. Anhydrous sodium sulfate removes water from the tissue and helps
to disintegrate the sample.
Apparatus
blender, high-speed; explosion-proof Waring Blendor, 1 qt jar
Büchner funnel (Büchner), porcelain, 12 cm diameter
chromatographic column, 25 mm id · 50 mm, plain
filter paper, Shark Skin
?
, to fit Büchner funnel
Kuderna-Danish concentrator (K-D), 500 mL or 1 L, with Snyder column,
plain receiving flask
vacuum filtration flask, 500 mL
Reagents
boiling chips, 20-30 mesh carborundum
petroleum ether, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? (Sample size may be adjusted to provide weight of fat appropriate to
cleanup step.) Weigh 25-50 g thoroughly ground and mixed fish or animal
tissue into blender jar. Add 100 g sodium sulfate.
? Alternately blend and mix with spatula until sample and sodium sulfate are
well mixed. Scrape down sides of blender jar and break up caked material
with spatula.
? Add 150 mL petroleum ether and blend at high speed 2 min.
? Decant petroleum ether supernate through Büchner fitted with two Shark
Skin
?
papers and filter with suction into vacuum filtration flask.
? Scrape down sides of blender jar and break up caked material with spatula.
? Re-extract residue in blender jar with two 100 mL portions petroleum
ether, blending 2 min each time. (After 1 min blending, stop blender,
scrape material from sides of blender jar and break up caked material with
spatula; continue blending 1 min.) Scrape down sides of blender jar and
break up caked material between extractions. Decant petroleum ether
supernates through Büchner and combine with first extract.
? After last blending, transfer residue from blender jar to Büchner, rinsing
blender jar and material in Büchner with three 25-50 mL portions
petroleum ether. Immediately after last rinse, press residue in Büchner
with bottom of clean beaker to force out remaining petroleum ether.
Pesticide Analytical Manual Vol. ISECTION 304
304–6
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
? Pour combined extracts and rinses through 25 mm · 50 mm column of
sodium sulfate and collect eluate in K-D with plain tube. Wash flask and then
column with small portions petroleum ether.
? Add boiling chip to K-D and evaporate most of petroleum ether from
combined extracts and rinses.
? Clean up extracted fat using one of the cleanup steps.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–7
Pesticide Analytical Manual Vol. I SECTION 304
E2 SMALL SCALE EXTRACTION OF FAT WITH SODIUM SULFATE,
PETROLEUM ETHER
Reference
Erney, D.R. (1974) J. Assoc. Off. Anal. Chem. 57, 576-579
Principles
Fat and residues are removed from fish and animal tissue by dissolving them in
petroleum ether. Anhydrous sodium sulfate removes water from the tissue and helps
to disintegrate the sample. Sample size and amounts of reagents are somewhat
reduced from amounts used in E1, for subsequent small scale cleanup of C7.
Apparatus
funnel, glass
homogenizer, Sorvall/Omni type, with 400 mL cup
volumetric flask (volumetric), 250 mL
Reagents
glass wool, Pyrex, see Section 204 for handling directions
petroleum ether, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Weigh 20 g thoroughly ground and mixed fish or animal tissue into
homogenizer cup. Moisten 40 g sodium sulfate with petroleum ether and
add to sample.
? Mix sample, using stirring rod, let stand 20 min, and mix again.
? Add 100 mL petroleum ether to sample and blend 1-2 min.
? Centrifuge balanced homogenizer cup at 2000 rpm 1-2 min to obtain clear
petroleum ether extract.
? Place glass wool plug in funnel, overlay with 20 g sodium sulfate, and place
funnel in 250 mL volumetric. Decant petroleum ether extract through
layer of sodium sulfate into volumetric.
? Mix sample again with stirring rod, add 100 mL petroleum ether, and
extract as before.
? Repeat extraction with 70 mL petroleum ether, combining all three
extractions in same 250 mL volumetric.
? Dilute to volume with petroleum ether.
? Clean up with C7, Florisil chromatography on 4 g column. No intermedi-
ate separation step is required if ￡ 0.2 g fat is used, as specified in C7.
? Note that this extraction yields a dilute solution of fat, rather than fat with
most solvent removed as in other extraction modules. To clean up this
extract with a module other than C7, solvent must first be removed.
Pesticide Analytical Manual Vol. ISECTION 304
304–8
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–9
Pesticide Analytical Manual Vol. I SECTION 304
E3 EXTRACTION OF FAT BY FILTERING
Reference
Mills, P.A. (1959) J. Assoc. Off. Agric. Chem. 42, 734-740
Principle
Fat and residues are removed from butter by melting and filtering to remove solids.
No extraction is needed for edible oil.
Apparatus
filter paper
funnel, glass
Directions
? Warm butter at about 50 C until fat separates; decant through dry filter
paper placed in glass funnel. Collect oil.
? Clean up extracted fat using one of the cleanup steps.
Pesticide Analytical Manual Vol. ISECTION 304
304–10
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–11
Pesticide Analytical Manual Vol. I SECTION 304
E4 EXTRACTION OF FAT WITH SOLVENTS FROM DENATURED PRODUCT
Reference
Mills, P.A. (1959) J. Assoc. Off. Agric. Chem. 42, 734-740
Principles
Fat and residues from cheese, milk, egg yolks, or dried whole eggs are dissolved in
ethyl ether and petroleum ether after the product has been denatured with oxalate
and alcohol. The ether extract is washed with large quantities of water to remove co-
extractives.
(Methodology for high fat egg products has not been studied extensively; this method
is recommended as the most applicable.)
Apparatus
blender, high-speed; explosion-proof Waring Blendor, 1 qt jar
centrifuge, explosion-proof, to hold 500 mL bottles
centrifuge bottle, glass, 500 mL. Use glass stopper or cover rubber stopper with
aluminum foil to avoid contamination.
chromatographic column, 25 mm id · 50 mm, plain
delivery tube apparatus (Figure 304-b), fabricated in laboratory
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, plain
receiving flask
separatory funnel (separator), 1 L
Reagents
alcohol, ethyl or methyl
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preservative;
see Section 204 for peroxide test
1+1 (v/v) ethyl ether/petroleum ether
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium chloride aqueous solution, saturated
sodium (or potassium) oxalate, reagent grade
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Cheese and Eggs—If experience with product indicates emulsions will not be
broken by centrifuging, add 1 mL water/2 g sample before blending. Place
25-100 g diced cheese or 25-50 g eggs (to provide about 3 g fat), about 2
g sodium or potassium oxalate, and 100 mL ethyl or methyl alcohol in
blender jar and blend 2-3 min. Pour blender contents into centrifuge
bottle.
Milk — Dilute evaporated milk with equal amount of water. Place 100 g
fluid milk or diluted evaporated milk into centrifuge bottle, add 100 mL
ethyl or methyl alcohol and about 1 g sodium or potassium oxalate, and
mix.
Pesticide Analytical Manual Vol. ISECTION 304
304–12
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
? To mixture in centrifuge bottle, add 50 mL ethyl ether and shake vigorously
1 min; then add 50 mL petroleum ether and shake vigorously 1 min.
? Centrifuge at about 1500 rpm about 5 min. Never leave stoppers in bottles
during centrifuging.
? Transfer solvent layer, with delivery tube apparatus, into separator contain
ing 500-600 mL water and 30 mL saturated sodium chloride solution. Re-
extract aqueous residue twice,
shaking vigorously with 50 mL
portions (1+1) ethyl ether/petro
leum ether; centrifuge and trans
fer solvent layer into separator
after each extraction.
? Cautiously mix combined extracts
and water. Drain and discard wa-
ter.
? Gently rewash solvent layer with
two 100 mL portions water, dis-
carding water each time. If emul-
sions form, add about 5 mL satu
rated sodium chloride solution to
solvent layer or include sodium
chloride with water wash.
? Pour ether solution through 25
mm · 50 mm column of sodium
sulfate and collect eluate in K-D
with plain tube. Wash separator
and then column with small por-
tions petroleum ether.
? Add boiling chip to K-D and evapo-
rate most of petroleum ether from
combined extracts and rinses.
? Clean up extracted fat using one
of the cleanup steps.
Glass tube, inserted in one hole of two-hole
rubber stopper, is used to draw upper solvent
layer from centrifuge bottle into separatory
funnel. Siphon tube is straight or bent in U-
shape and inlet end placed at interface of two
phases in centrifuge bottle. Second hole in
stopper is fitted with another glass tube.
Vacuum drawn through second tube causes
upper phase from centrifuge bottle to transfer
into separator.
(Corrigan, E. (Nov. 1963) (FDA) Bureau By-Lines 5, 20;
Sawyer, L.D., and Baca, J.R. (May 1978) LIB 2188, FDA,
Rockville, MD.)
Figure 304-b
Delivery Tube Apparatus
Vacuum
Rubber
stopper
with two
holes
Glass tubing
Inlet
Delivery
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–13
Pesticide Analytical Manual Vol. I SECTION 304
E5 EXTRACTION OF FAT WITH SOLVENTS
Reference
Sawyer, L.D. (1982) J. Assoc. Off. Anal. Chem. 65, 1122-1128
Principles
Fat and residues are removed from ground oilseeds, high fat feeds or feed materials,
grains, or nuts by dissolving in petroleum ether and ethyl ether, followed by ethyl
alcohol. The organic extract is washed with large quantities of water to remove co-
extractives.
Apparatus
centrifuge, explosion-proof, to hold 500 mL bottles
chromatographic column, 25 mm id, plain
homogenizer, Polytron Model PT 10-35, with PT 35K generator containing
knives, head equipped with metal (not Teflon) bushing or Sorvall/Omni type
homogenizer jar, Sorvall/Omni stainless steel cup, 400 mL, or centrifuge
bottle, glass, 500 mL
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, plain
receiving flask
separatory funnels (separators), 1 L
Reagents
alcohol, ethyl
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preservative;
see Section 204 for peroxide test
1+1 (v/v) ethyl ether/petroleum ether
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium chloride aqueous solution, saturated
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
Directions
? Weigh 50 g ground sample of oilseeds, high fat feeds or feed materials,
grains, or nuts in Sorvall/Omni cup or in centrifuge bottle. Add 200 mL
petroleum ether and blend 1.5 min at high speed with Polytron PT 10-35
homogenizer or Omni-Mixer.
? Centrifuge extraction vessel and decant solvent into 500 mL beaker. Never
leave stoppers in bottles during centrifuging.
? Add 150 mL (1+1) ethyl ether/petroleum ether to vessel and blend;
centrifuge and decant into same beaker as before.
? Set beaker containing combined ethers under gentle air stream to concen-
trate to about 100 mL.
? Re-extract residue in extraction vessel with 150 mL ethyl alcohol for 1.5
min. Centrifuge and decant solvent into 1 L separator.
Pesticide Analytical Manual Vol. ISECTION 304
304–14
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
? Add 50 mL ethyl alcohol to extraction vessel, wash residue in vessel by gently
blending, then centrifuge and decant into same separator as before.
? Add concentrated ethers from first two extractions to separator. Rinse
beaker using small (about 5 mL) petroleum ether washes and add washes
to separator.
? Mix separator contents well and add 600 mL water and about 40 mL
saturated sodium chloride solution.
? Hold separator in horizontal position and mix thoroughly 45 sec. Let
layers separate and drain aqueous portion into second 1 L separator
containing 100 mL petroleum ether.
? Mix contents of second separator thoroughly about 15 sec and let layers
separate. Drain and discard aqueous portion and drain petroleum ether
into original separator. Wash combined ethers with two 100 mL portions
water.
? Pour ether solution through 25 mm · 50 mm column of sodium sulfate and
collect eluate in K-D with plain tube. Wash separator and then column with
small portions petroleum ether.
? Add boiling chip to K-D and evaporate most of petroleum ether from
combined extracts and rinses in K-D.
? Clean up extracted fat using one of the cleanup steps.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–15
Pesticide Analytical Manual Vol. I SECTION 304
C1 ACETONITRILE-PETROLEUM ETHER PARTITIONING, FLORISIL COLUMN
CLEANUP, THREE MIXED ETHER ELUANTS
Reference
Mills, P.A. (1959) J. Assoc. Off. Agric. Chem. 42, 734-740
Principles
Extracted fat is carefully weighed to avoid overloading the capacity of the cleanup
step. Pesticide residues are isolated from fat by partition between petroleum ether and
acetonitrile. Most of the fat is retained in petroleum ether while residues partition into
acetonitrile in proportion to their partitioning coefficient in that system. In the
subsequent step, residues in acetonitrile are partitioned back into petroleum ether
when added water reduces their solubility in acetonitrile.
Residues in solution are separated from sample co-extractives on a column of Florisil
adsorbent; eluants of increasing polarity sequentially remove residues from the
column.
Cleanup steps C2, C3, and C4 offer alternative Florisil elution systems. The eluants
used in C2 produce different elution patterns than C1, which can sometimes be
valuable for confirmation. C2 can also be used as an additional cleanup step.
C3 or C4 are used for analyses directed at the determination of polychlorinated
biphenyls. The Florisil column is eluted with petroleum ether prior to elution with the
other mixtures, in order to separate the polychlorinated biphenyls from most
pesticide residues and to provide a cleaner extract for their determination.
Apparatus
chromatographic column, 25 mm id · 50 mm, plain
chromatographic column, 22 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, volumetric or graduated receiving flask
separatory funnels (separators), 125 mL and 1 L
Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distillation
directions
acetonitrile saturated with petroleum ether
boiling chips, 20-30 mesh carborundum
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preservative;
see Section 204 for peroxide test
Florisil, PR grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
hexane, distilled from all-glass apparatus
methylene chloride, distilled from all-glass apparatus
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium chloride aqueous solution, saturated
Pesticide Analytical Manual Vol. ISECTION 304
304–16
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for han-
dling directions
eluants: 6% (v/v) ethyl ether/petroleum ether
15% (v/v) ethyl ether/petroleum ether
50% (v/v) ethyl ether/petroleum ether
Directions
? Cleanup is applicable to ￡ 3 g fat. Evaporate solvent from solution of
extracted fat and determine amount of fat extracted by one of the following
operations:
– When total amount of fat in sample is expected to be >3 g and analysis
is not for volatile residues, transfer concentrated solution to tared
beaker, using small amounts of petroleum ether, and evaporate to
dryness at steam bath temperature under current of dry air. Weigh and
record weight of fat extracted. Take ￡ 3 g fat for cleanup. Calculate
weight of sample analyzed as:
weight fat taken for cleanup
weight fat extracted
· weight original sample
– When it is known that amount of fat in sample is <3 g, do not evaporate
solvent further but clean up total amount of fat solution. Calculate
weight of sample analyzed as: weight original sample.
– When it is known that fat content is >3 g, or that residue level is high, do
not evaporate solvent further. Adjust to known, appropriate volume,
transfer aliquot to tared beaker, evaporate solvent from aliquot, and
weigh to determine fat content. Clean up aliquot of volume containing
￡ 3 g fat. Calculate weight of sample analyzed as:
volume fat solution taken for cleanup
total volume of solution
· weight original sample
– When analysis for volatile chemicals is desirable, do not evaporate
petroleum ether at steam bath temperature. Adjust to known, appropri-
ate volume, transfer aliquot to tared beaker, evaporate solvent from
aliquot, and weigh to determine fat content. Clean up remaining
solution or appropriate aliquot. Calculate weight of sample analyzed as:
weight fat solution taken for cleanup
total volume of solution
· weight original sample
Acetonitrile/Petroleum Ether Partitioning
? Weigh ￡ 3 g fat into 125 mL separator, and add petroleum ether so that total
volume of fat and petroleum ether in separator is 15 mL. Take smaller
weight of fish oil if experience indicates tendency to emulsion formation
during partitioning.
? Add 30 mL acetonitrile saturated with petroleum ether, shake vigorously
1 min, let layers separate, and drain acetonitrile into 1 L separator contain-
ing 650 mL water, 40 mL saturated sodium chloride solution, and 100 mL
petroleum ether.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–17
Pesticide Analytical Manual Vol. I SECTION 304
? Extract petroleum ether solution in 125 mL separator with three addi-
tional 30 mL portions acetonitrile saturated with petroleum ether, shaking
vigorously 1 min each time, and combine all extracts in the 1 L separator.
? Hold 1 L separator in horizontal position and mix thoroughly 30-45 sec.
Let layers separate and drain aqueous layer into second 1 L separator.
? Add 100 mL petroleum ether to second 1 L separator, shake vigorously 15
sec, and let layers separate. Discard aqueous layer, combine petroleum
ether with petroleum ether in original 1 L separator, and wash with two 100
mL portions water.
? Discard washings and drain petroleum ether layer through 25 mm · 50
mm column of sodium sulfate into K-D. Rinse separator and then column
with three 10 mL portions petroleum ether.
? Add boiling chip to K-D and evaporate combined extract and rinses to 5-
10 mL for transfer to Florisil column.
Florisil Column Cleanup
? Place activated Florisil (4" or weight determined by lauric acid value) in 22
mm id column; add about 0.5" sodium sulfate. Prewet column with 40-50
mL petroleum ether. Place K-D with volumetric or graduated receiving
flask under column to receive eluate.
? Transfer sample extract solution to column, letting it pass through at
about 5 mL/min. Rinse container (and sodium sulfate if present) with two
5 mL portions petroleum ether, transfer rinsings to column, and rinse
walls of chromatographic tube with additional small portions petroleum
ether.
? Elute column at about 5 mL/min with 200 mL 6% ethyl ether/petroleum
ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 15% ethyl ether/
petroleum ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 50% ethyl ether/
petroleum ether eluant.
? Add boiling chips to K-Ds and concentrate each eluate to suitable definite
volume. When volume <5 mL is needed, use two-ball micro-Snyder or
micro-Vigreaux column during final evaporation in receiving flask.
? Use appropriate determinative steps, such as DG1 or DG13, DG7, and
DG10, to identify and measure residues. First eluate (6%) is usually
suitable for GLC determination without further cleanup.
Pesticide Analytical Manual Vol. ISECTION 304
304–18
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
ALTERNATIVES:
C2 ACETONITRILE-PETROLEUM ETHER PARTITIONING, FLORISIL
COLUMN CLEANUP, THREE METHYLENE CHLORIDE ELUANTS
Reference
Mills, P.A., et al. (1972) J. Assoc. Off. Anal. Chem. 55, 39-43
Principles
Florisil is eluted with mixtures of methylene chloride, hexane, and acetonitrile. The
resulting second eluate is cleaner than the second eluate of C1, although 90% of the
fat placed on the column is eluted by the third eluant. The eluants can elute pesticide
chemicals of a greater polarity than can be eluted by C1. C2 is preferred for analysis
of fats and oils, for residues of endosulfan, and for separation of heptachlor epoxide
and octachlor epoxide.
Additional Reagents
eluants: 1—20% methylene chloride/hexane (v/v). Dilute 200 mL methyl-
ene chloride with hexane. Allow mixture to reach room tempera-
ture, and adjust volume to 1 L with hexane.
2—50% methylene chloride/0.35% acetonitrile/49.65% hexane (v/
v/v). Pipet 3.5 mL acetonitrile into 500 mL methylene chloride and
dilute with hexane. Allow mixture to reach room temperature and
adjust to 1 L with hexane.
3—50% methylene chloride/1.5% acetonitrile/48.5% hexane (v/
v/v). Pipet 15 mL acetonitrile into 500 mL methylene chloride and
dilute with hexane. Allow mixture to reach room temperature and
adjust to 1 L with hexane.
Directions
? Follow C1 above, except replace directions for Florisil cleanup with the
following:
? Place activated Florisil (4" or weight determined by lauric acid value) in 22
mm id column; add about 0.5" sodium sulfate. Prewet column with 40-50
mL hexane. Place K-D with volumetric or graduated receiving flask under
column to receive eluate.
? Transfer sample extract solution to column, letting it pass through at about
5 mL/min. Rinse container (and sodium sulfate if present) with two 5 mL
portions hexane, transfer rinsings to column, and rinse walls of chromato-
graphic tube with additional small portions hexane.
? Elute column at about 5 mL/min with 200 mL eluant 1.
? Change K-Ds and elute with 200 mL eluant 2.
? Change K-Ds and elute with 200 mL eluant 3.
? Add boiling chips to K-Ds and concentrate each eluate to suitable definite
volume. When volume <5 mL is needed, use two-ball micro-Snyder or micro-
Vigreaux column during evaporation.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–19
Pesticide Analytical Manual Vol. I SECTION 304
C3 ACETONITRILE-PETROLEUM ETHER PARTITIONING, FLORISIL COLUMN
CLEANUP, PETROLEUM ETHER AND THREE MIXED ETHER ELUANTS
Reference
Reynolds, L.M. (1969) Bull. Environ. Contam. Toxicol. 4, 128-143
Principles
Polychlorinated biphenyls are separated from most pesticide residues by elution of
Florisil column with petroleum ether prior to elution with ethyl ether/petroleum
ether mixtures.
Directions
? Follow C1 above, except insert the following before elution of Florisil
column with 6% ethyl ether/petroleum ether:
? Elute column at about 5 mL/min with 250 mL petroleum ether. Change
K-Ds.
C4 ACETONITRILE-PETROLEUM ETHER PARTITIONING, FLORISIL COLUMN
CLEANUP, PETROLEUM ETHER AND THREE METHYLENE CHLORIDE
ELUANTS
Reference
Reynolds, L.M. (1969) Bull. Environ. Contam. Toxicol. 4, 128-143
Principles
Polychlorinated biphenyls are separated from most pesticide residues by elution of
Florisil column with petroleum ether prior to elution with methylene chloride
mixtures.
Directions
? Follow C3 above, except insert the following before elution of Florisil
column with eluant 1:
? Elute column at about 5 mL/min with 250 mL petroleum ether. Change
K-Ds.
Pesticide Analytical Manual Vol. ISECTION 304
304–20
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–21
Pesticide Analytical Manual Vol. I SECTION 304
C5 GEL PERMEATION CHROMATOGRAPHY (GPC)
References
Griffitt, K.R., and Craun, J.C. (1974) J. Assoc. Off. Anal. Chem. 57, 168-172
Hopper, M.L (1982) J. Agric. Food Chem. 30, 1038-1041
Principles
Fat is separated from residues by gel permeation (size exclusion) chromatography.
The solution of fat extracted from fatty food is placed on a column and eluted with
solvents. The fat is eluted first and discarded, leaving residues in the next portion of
eluant.
Cleanup C6 offers optional Florisil column cleanup subsequent to GPC.
Apparatus
filtration device for solutions, 10 mL syringe with Luer-Lok tip, fitted with
either (a) 13 mm diameter Swinny stainless steel filter holder and 13 mm
diameter filters, 5.0 m m LS-type, or (b) disposable membrane filters, 25 mm
diameter, 5 m m Teflon membrane, encased in polypropylene. (Pre-assembled
devices that do not require a syringe are also available.)
GPC apparatus; automated equipment optional but recommended. GPC
apparatus must include:
1) sample introduction valve
2) pump, low pressure, suitable for use with organic solvents, capable of
5 mL/min flow
3) sample loading loop, 1/16" Teflon tubing coiled in cylindrical form,
about 13 mL capacity
4) pulse dampener, about 6' of 1/8" copper tubing coiled and closed at one
end, installed between pump and sample introduction valve with a con-
necting tee. Pulse dampener is needed only when pump is not pulseless.
GPC column, glass, 25 mm id · 300 or 500 mm with organic solvent plunger
kit
GPC syringe, 10 mL syringe with Luer-Lok tip, with Millipore Swinny stain-
less steel adapter, Millipore 5.0 m m LS-type filter
graduated cylinder (graduate), glass-stoppered (g-s), calibrated
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated receiving flask
Reagents
acetone, distilled from all-glass apparatus
Bio-Beads SX-3 resin, 200-400 mesh (Bio-Rad Laboratories, Richmond, CA;
pretested resin is available from ABC Laboratories)
hexane, distilled from all-glass apparatus
methylene chloride, distilled from all-glass apparatus
eluant: 50% (v/v) methylene chloride/hexane
Pesticide Analytical Manual Vol. ISECTION 304
304–22
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
Preparation of GPC Column
? Weigh 35 g Bio-Beads SX-3 into 400 mL beaker.
? Add 150 mL 50% methylene chloride/hexane.
? Stir beads with glass or steel rod until all beads have swelled and no clumps
are present.
? Pour slurry into GPC column with aid of stirring rod.
? Hold column in upright position with plunger tightened about 25 mm from
bottom of usable length of column, ignoring threaded ends.
? Continuously add slurry to column so beads never become completely
settled until all beads have been added.
? Place other plunger in column after beads have settled and liquid has
drained off.
? Compress each plunger equal distance from its respective end until bed
length is about 200 mm.
? Connect column to GPC solvent delivery system, and pump solvent from
bottom to top of column until all air is expelled.
? Adjust flow rate of system to 5 mL/min and check column pressure. Adjust
operating pressure for column to 8-11 psig by moving plunger(s).
? Allow GPC system to equilibrate by pumping solvent through it.
? Re-adjust flow rate to 5 mL/min if it has changed.
Calibration of GPC Column
Elution of Fat
? Melt and filter butter through fluted filter paper into suitable container.
? Weigh 5 g warm filtered butter (do not include water layer) into 25 mL
g-s graduate; dilute to 25 mL with 50% methylene chloride/hexane; mix
until fat is dissolved (0.2 g fat/mL).
? Filter fat solution through filtration device and load 5 mL fat solution onto
GPC column.
? Elute with 50% methylene chloride/hexane.
? Collect column effluent in tared beakers in 10 mL increments from 0 to 100
mL.
? Evaporate solvent, cool and weigh beakers to calculate amount fat eluted in
each 10 mL increment. (For manual GPC, collect 10 mL fractions in
separate graduates and transfer to tared beakers for evaporation and
calculation of fat.)
? Most (98%) fat should elute in first 60 mL. If >5% of fat appears in 60-70 mL
fraction or later, reject column and prepare new one by repacking with
original batch of beads. Visual evaluation of yellow fat band as it passes
through column usually shows tailing or streaking when column is inad-
equate. Use new batch of beads if second column is still inadequate.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–23
Pesticide Analytical Manual Vol. I SECTION 304
Elution of Pesticides
? Prepare mixed standard solution containing 0.2 m g diazinon/mL, 0.6 m g
ethion/mL, 0.1 m g lindane/mL, 0.4 m g parathion/mL, and 0.05 m g
pentachloroaniline/mL in 50% methylene chloride/hexane.
? Filter mixed standard solution through filtration device and load 5 mL
onto GPC column
? Elute with 50% methylene chloride/hexane.
? Collect 10 mL fractions from 0 through 160 mL.
? Transfer each fraction to K-D fitted with graduated receiving flask and add
50 mL hexane and 2-3 boiling chips; concentrate each to 10 mL.
? Use determinative steps DG2 and DG3 (Section 302) to calculate recover-
ies; column is normal if diazinon and ethion start to elute in either 50-60
mL or 60-70 mL fraction, and lindane starts to elute in 90-100 mL fraction.
? Determine what volume should be discarded (usually first 60 mL) and
what should be collected (usually 60-160 mL fraction) by examining fat
and mixed standard elution profiles developed above. Use these cali-
brated fraction volumes in subsequent calibration steps and in sample
cleanup.
Directions
? Use GPC column prepared and calibrated as described above. Column
can be used repeatedly.
? Method is applicable to ￡ 1 g fat sample in 5 mL; better cleanup is provided
if weight of fat in 5 mL is restricted to 0.75 g.
? Concentrate solution of extracted fat to small volume. Add 100 mL
methylene chloride and reconcentrate.
? Based on estimate of weight of fat in extract, use calibrated graduate large
enough to create final solution containing ￡ 0.2 g/mL. Transfer concen-
trated solution to graduate. Add enough methylene chloride to provide
half the final volume, then fill to final volume with hexane.
? Pipet 1 mL into tared beaker; evaporate solvent and weigh. If weight is >0.2
g, adjust concentration of remaining solution to ￡ 0.2 g/mL with 50%
methylene chloride/hexane.
? Centrifuge cloudy solutions before loading them onto GPC. Filter all
solutions through filtration device before GPC.
? Fill GPC sample loading loops with extract using GPC syringe. Load 5 mL
fat solution (equivalent to ￡ 1 g fat) onto GPC column. Load more than one
loop with same solution if needed to increase final total sample equivalent.
? Elute column with 160 mL 50% methylene chloride/hexane. Collect and
discard volume previously calibrated to contain fat. Separately collect final
portion, previously calibrated to contain residues.
? Transfer GPC eluate to K-D with 5 mL graduated receiving flask and
concentrate to <3 mL. Add hexane and reconcentrate to <1 mL.
Pesticide Analytical Manual Vol. ISECTION 304
304–24
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
? Use appropriate determinative steps to identify and measure residues.
Dilute final concentrated eluate with acetone for determination of organo-
phosphorus residues by DG2 or DG14 (Section 302). Dilute with hexane for
determination of organohalogen residues by DG3 or DG16. Clean up on
Florisil (C6) before determination of residues with electron capture detec-
tor (DG1, 7, 10, and 13).
ALTERNATIVE:
C6 GPC, FLORISIL COLUMN (4 G) CLEANUP, THREE METHYLENE
CHLORIDE ELUANTS
Reference
Griffitt, K.R., et al. (July 1983) “Miniaturized Florisil Column Cleanup of Chlorinated
and Organophosphate Eluates in Total Diet Samples,” LIB 2722, FDA, Rockville, MD
Principles
For additional cleanup of samples, residues are further separated from sample co-
extractives on a small column of Florisil adsorbent; three eluants of increasing
polarity sequentially remove residues from the column.
Additional Apparatus
chromatographic column, 10 mm id · 300 mm, Teflon stopcock, coarse porosity
fritted disc
Additional Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distillation
directions
Florisil, PR grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for han-
dling directions
eluants: 1—20% methylene chloride/hexane (v/v). Dilute 200 mL methylene
chloride with hexane. Allow mixture to reach room temperature,
and adjust volume to 1 L with hexane.
2—50% methylene chloride/0.35% acetonitrile/49.65% hexane (v/
v/v). Pipet 3.5 mL acetonitrile into 500 mL methylene chloride and
dilute with hexane. Allow mixture to reach room temperature and
adjust to 1 L with hexane.
3—50% methylene chloride/1.5% acetonitrile/48.5% hexane (v/v/
v). Pipet 15 mL acetonitrile into 500 mL methylene chloride and
dilute with hexane. Allow mixture to reach room temperature and
adjust to 1 L with hexane.
Directions
? Follow directions of C5 up through elution of GPC column. Concentrate
GPC eluate to <5 mL.
? Place activated Florisil (weight = 110/lauric acid value · 4 g) in 10 mm
chromatographic column; add about 2 cm sodium sulfate. Completely
open stopcock and tap column to settle adsorbent. Prewet column with
5 mL hexane. Do not allow column to go dry. Place K-D with volumetric
or graduated receiving flask under column to receive eluate.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–25
Pesticide Analytical Manual Vol. I SECTION 304
? Transfer concentrated GPC eluate to column, letting it pass through at
about 5 mL/min. Rinse container with two 3 mL portions hexane, transfer
rinsings to column, and rinse walls of chromatographic tube with addi-
tional small portions hexane.
? Elute column at about 5 mL/min with 35 mL eluant 1.
? Change K-Ds and elute with 35 mL eluant 2.
? Change K-Ds and elute with 40 mL eluant 3.
? Concentrate each eluate to suitable definite volume in K-D. When volume
<5 mL is needed, use two-ball micro-Snyder or micro-Vigreaux column
during evaporation.
Pesticide Analytical Manual Vol. ISECTION 304
304–26
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–27
Pesticide Analytical Manual Vol. I SECTION 304
C7 FLORISIL COLUMN (4 G) CLEANUP, TWO MIXED ETHER ELUANTS,
OPTIONAL ALKALINE HYDROLYSIS
References
Erney, D.R. (1974) J. Assoc. Off. Anal. Chem. 57, 576-579
Erney, D.R. (1983) J. Assoc. Off. Anal. Chem. 66, 969-973
Principles
Residues are separated from fat on a small column of Florisil adsorbent. Because no
prior isolation step is included to minimize co-extractives, only 0.2 g extracted fat is
placed on the Florisil column. Two eluants of increasing polarity sequentially remove
residues from the column. The second eluate is cleaned up further with alkaline
hydrolysis if needed, a step applicable only to chemicals stable to hot alkali.
Apparatus
chromatographic column, 10 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
Kuderna-Danish concentrator (K-D), 125 mL, with Snyder column, two-ball
micro-Snyder column, graduated and 10 mL volumetric receiving flask
Reagents
boiling chips, 20-30 mesh carborundum
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preservative;
see Section 204 for peroxide test
Florisil, PR grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
hexane, distilled from all-glass apparatus
petroleum ether, distilled from all-glass apparatus
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for
handling directions
eluants: 6% (v/v) ethyl ether/petroleum ether
15% (v/v) ethyl ether/petroleum ether
2% (w/v) potassium hydroxide in methanol or ethanol
1+1 (v/v) water/alcohol
Directions
Florisil Column Cleanup
? Cleanup is applicable to ￡ 0.2 g fat.
? Concentration of fat in extract prepared by E2 is about ￡ 0.2 g in 25 mL. To
use this cleanup for extracts prepared by E1, E3, E4, or E5, first dilute all
or part of extracted fat to ￡ 0.2 g in 25 mL.
? Transfer 25 mL aliquot to tared beaker and place on steam bath until
solvent is evaporated. Leave on steam bath additional 30 min, remove, and
cool. Weigh fat.
? If extract contains ￡ 0.2 g/25 mL, transfer 25 mL aliquot to 125 mL K-D
with graduated receiving flask. If extract contains >0.2 g/25 mL, transfer
volume containing ￡ 0.2 g fat to K-D.
Pesticide Analytical Manual Vol. ISECTION 304
304–28
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
? Add several boiling chips and concentrate solution to about 3 mL on steam
bath. Let cool, remove Snyder column, rinse K-D with two 1 mL portions
petroleum ether. Use current of air to concentrate sample to 3 mL.
? Place activated Florisil (weight = 110/lauric acid value· 4 g) in 10 mm id
glass column; add about 2 cm sodium sulfate. Completely open stopcock,
tap tube to settle adsorbent, and mark tube 1 cm above sodium sulfate layer.
? Add about 25 mL petroleum ether to Florisil column. As solvent level
reaches mark, place 125 mL K-D with 10 mL volumetric receiving flask
under column.
? Using disposable pipet, transfer 3 mL concentrated sample extract to
column; wash flask with 1 mL petroleum ether and add wash to column.
Solvent level must not go below mark; temporarily close stopcock if
necessary.
? Elute column with 35 mL 6% ethyl ether/petroleum ether.
? When solvent level reaches mark, change K-Ds. Elute column with 35 mL
15% ethyl ether/petroleum ether.
? Concentrate each eluate to suitable definite volume in K-D. When volume
<5 mL is needed, use two-ball micro-Snyder or micro-Vigreaux column
during evaporation.
? Use appropriate determinative steps, such as DG1 or DG13, DG7, and
DG10, to identify and measure residues. Second eluate may need further
cleanup prior to GLC; use optional alkaline hydrolysis if residues are stable
to hot alkali.
Optional Alkaline Hydrolysis
? Concentrate 15% ethyl ether/petroleum ether eluate to 2 mL with current
of air.
? Add 1 mL 2% potassium hydroxide/alcohol, attach micro-Snyder column
to flask, and carefully reduce volume to ￡ 1 mL on steam bath. Reflux 15 min,
then let cool.
? Add 2 mL (1+1) water/alcohol and 5 mL hexane to flask, and shake 1 min.
Centrifuge to separate layers.
? Transfer as much hexane layer as possible to second flask, using disposable
pipet.
? Add another 5 mL hexane to flask, and repeat extraction.
? Concentrate combined hexane extracts to appropriate volume for determi-
nation.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–29
Pesticide Analytical Manual Vol. I SECTION 304
C8 DISPERSION ON ALUMINA, FLORISIL COLUMN CLEANUP,
THREE MIXED ETHER ELUANTS
References
Luke, M.A., and Doose, G.M. (Jan. 1978) “A Rapid Analysis for Pesticide Residues in
Milk and Other Fatty Foods,” LIB 2120A, FDA, Rockville, MD
Gillespie, A.M., and Walters, S.M. (May 1983) “An Alumina Blending Technique for
the Separation of Pesticides from Lipids (Based on LIB 2120A),” LIB 2716, FDA,
Rockville, MD
Principles
Extracted fat is dispersed on deactivated alumina and pesticide residues are removed
with a mixture of water and acetonitrile; most of the fat is retained by the alumina. In
the subsequent step, residues in acetonitrile are partitioned back into petroleum
ether when added water reduces their solubility in acetonitrile. Residues in solution
are separated from remaining sample co-extractives on a column of Florisil adsorbent;
three eluants of increasing polarity sequentially remove residues from the column.
Cleanup step C9 offers an alternative Florisil elution system, which produces different
elution patterns than C8.
Apparatus
Büchner funnel (Büchner), porcelain, 12 cm diameter
chromatographic column, 25 mm id · 50 mm, plain
chromatographic column, 22 mm id · 300 mm, Teflon stopcock, coarse
porosity fritted disc
filter paper, Whatman No. 40, 15 cm diameter. Wash paper by soaking in 20%
water/acetonitrile to remove substances that interfere in GLC determination.
Dry and store in closed container.
homogenizer, Sorvall/Omni type, with 400 mL cup
Kuderna-Danish concentrator (K-D), 500 mL, with Snyder column, two-ball
micro-Snyder column, graduated and volumetric receiving flasks
separatory funnel (separator), 1 L
shaker, mechanical, Burrell wrist action
Reagents
acetonitrile, distilled from all-glass apparatus; see Section 204 for distillation
directions
alumina, Fisher Adsorption Alumina, No. A-540, 80-200 mesh
boiling chips, 20-30 mesh carborundum
ethyl ether, distilled from all-glass apparatus, with 2% ethanol as preservative;
see Section 204 for peroxide test
Florisil, PR grade; see Section 204 for handling and testing directions and
calculation of lauric acid value
glass wool, Pyrex; see Section 204 for handling directions
hexane, distilled from all-glass apparatus
methylene chloride, distilled from all-glass apparatus
Pesticide Analytical Manual Vol. ISECTION 304
304–30
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
petroleum ether, distilled from all-glass apparatus
sodium chloride, reagent grade
sodium chloride aqueous solution, saturated
sodium sulfate, anhydrous, granular, reagent grade; see Section 204 for han-
dling directions
20% (v/v) water/acetonitrile
eluants: 6% (v/v) ethyl ether/petroleum ether
15% (v/v) ethyl ether/petroleum ether
50% (v/v) ethyl ether/petroleum ether
Preparation of Alumina
? Wash alumina to remove substances that interfere in GLC determination.
Soak in methylene chloride ? 1 hr; decant and discard methylene chloride.
Soak in hexane ? 1 hr; decant and discard hexane. Dry alumina on steam
bath.
? Place washed and dried alumina in 260 C muffle furnace 4 hr. Transfer to
tightly closed container and withdraw convenient amounts (e.g., 500 g) for
deactivation. Add water incrementally to final concentration of ? 16% (w/
w) but ￡ 19% (w/w), shaking briefly after each addition. Caution: heat will
be produced when water is added. Shake ? 4 hr on mechanical shaker. Store
in tightly closed container. Alumina thus prepared has been found to be
stable for at least 4 mon.
Directions
Dispersion on Alumina
? Cleanup is applicable to ￡ 2 g fat.
? Transfer concentrated solution of extracted fat to tared beaker, using small
amounts of petroleum ether, and evaporate to dryness at steam bath
temperature under current of dry air. Weigh and record weight of fat
extracted. Calculate weight of sample analyzed as:
weight fat taken for cleanup
weight fat extracted
· weight original sample
? Weigh ￡ 2 g fat into 150 mL beaker containing 50 g deactivated alumina; mix
well.
? Transfer mixture to homogenizer cup and add 350 mL 20% water/
acetonitrile. Blend 2-4 min at high speed.
? Transfer most of contents, without rinsing, to Buchner fitted with filter
paper; filter without suction. Alternatively, centrifuge blended contents
5 min at 1500 rpm and decant supernate through glass funnel with glass
wool.
? Record mL solvent recovered; calculate g sample as:
mL solvent recovered
350
g sample = g fat ·
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–31
Pesticide Analytical Manual Vol. I SECTION 304
Partitioning
? Transfer filtrate to 1 L separator containing 100 mL petroleum ether and
shake vigorously 30 sec.
? Add 10 mL saturated sodium chloride solution and 500 mL water.
? Hold 1 L separator in horizontal position and thoroughly mix 30-45 sec.
Let layers separate and drain aqueous layer into second 1 L separator.
? Add 100 mL petroleum ether to second 1 L separator, shake vigorously 15
sec, and let layers separate. Discard aqueous layer, combine petroleum
ether with petroleum ether in original separator, and wash with two 100
mL portions water.
? Discard washings and drain petroleum ether layer through 25 mm · 50
mm column sodium sulfate into 500 mL K-D. Rinse separator and then
column with three 10 mL portions petroleum ether.
? Add boiling chip to K-D and concentrate combined extract and rinses to
5-10 mL for transfer to Florisil column.
Florisil Column Cleanup
? Place activated Florisil (4" or weight determined by lauric acid value) in 22
mm id glass column; add about 0.5" anhydrous sodium sulfate. Prewet
column with 40-50 mL petroleum ether. Place K-D with volumetric or
graduated receiving flask under column to receive eluate.
? Transfer sample extract solution to column, letting it pass through at
about 5 mL/min. Rinse container (and sodium sulfate if present) with two
5 mL portions petroleum ether, transfer rinsings to column, and rinse
walls of chromatographic tube with additional small portions petroleum
ether.
? Elute column at about 5 mL/min with 200 mL 6% ethyl ether/petroleum
ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 15% ethyl ether/
petroleum ether eluant.
? Change K-Ds and elute at about 5 mL/min with 200 mL 50% ethyl ether/
petroleum ether eluant.
? Add boiling chips to K-Ds and concentrate each eluate to suitable definite
volume. When volume <5 mL is needed, use two-ball micro-Snyder or
micro-Vigreaux column during final evaporation in receiving flask.
? Use appropriate determinative steps, such as DG1 or DG13, DG7, and
DG10, to identify and measure residues.
Pesticide Analytical Manual Vol. ISECTION 304
304–32
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
ALTERNATIVE:
C9 DISPERSION ON ALUMINA, FLORISIL COLUMN CLEANUP,
THREE METHYLENE CHLORIDE ELUANTS
Principles
Florisil is eluted with mixtures of methylene chloride, hexane, and acetonitrile. The
resulting second eluate is cleaner than the second eluate of C8, although 90% of the
fat placed on the column is eluted by the third eluant. The eluants can elute pesticide
chemicals of a greater polarity than can be eluted by C8. C9 is preferred for analysis
of fats and oils, for residues of endosulfan, and for separation of heptachlor epoxide
and octachlor epoxide.
Additional Reagents
eluants: 1—20% methylene chloride in hexane (v/v). Dilute 200 mL
methylene chloride with hexane. Allow mixture to reach room
temperature, and adjust volume to 1 L with hexane.
2—50% methylene chloride/0.35% acetonitrile/49.65% hexane
(v/v/v). Pipet 3.5 mL acetonitrile into 500 mL methylene chloride
and dilute with hexane. Allow mixture to reach room temperature
and adjust to 1 L with hexane.
3—50% methylene chloride/1.5% acetonitrile/48.5% hexane
(v/v/v). Pipet 15 mL acetonitrile into 500 mL methylene chloride
and dilute with hexane. Allow mixture to reach room temperature
and adjust to 1 L with hexane.
Directions
? Follow C8 above, except replace the directions for Florisil column cleanup
with the following:
? Place activated Florisil (4" or weight determined by lauric acid value) in
22 mm id glass column; add about 0.5" anhydrous sodium sulfate. Prewet
column with 40-50 mL hexane. Place K-D with volumetric or graduated
receiving flask under column to receive eluate.
? Transfer sample extract solution to column letting it pass through at about
5 mL/min. Rinse container (and sodium sulfate if present) with two 5 mL
portions hexane, transfer rinsings to column, and rinse walls of chromato-
graphic tube with additional small portions hexane.
? Elute column at about 5 mL/min with 200 mL eluant 1.
? Change K-Ds and elute with 200 mL eluant 2.
? Change K-Ds and elute with 200 mL eluant 3.
? Add boiling chips to K-Ds and concentrate each eluate to suitable definite
volume. When volume <5 mL is needed, use two-ball micro-Snyder or micro-
Vigreaux column during final evaporation in receiving flask.
? Use appropriate determinative steps, such as DG1 or DG13, DG7, and
DG10, to identify and measure residues.
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92) 304–33
Pesticide Analytical Manual Vol. I SECTION 304
DETERMINATION
Inject concentrated extract equivalent to ￡ 3 mg fat (or 20 mg whole product) into the
following GLC systems (Section 302) for determination of residues.
Minimum recommended determinations:
DG1 or DG13 residues with halogen, sulfur, or other moieties
or
DG3 or DG16 organohalogen residues
DG10 late eluting residues, especially pyrethroids
or
DG12 late eluting organohalogen residues, especially pyrethroids
DG7 early eluting residues with halogen, sulfur, or other moieties
DG2 or DG14 organophosphorus residues; large amounts of sulfur may
interfere
DG4 organonitrogen residues; selective to nitrogen, but co-extrac-
tives may contain nitrogen
DG5 or DG17 organonitrogen and organophosphorus residues
For accurate quantitation, reference standards should be dissolved in same solvent
as concentrated extract, only peaks >10% FSD should be measured, and peak sizes
of residue and reference standard should match within – 25%.
See Chapter 5 for additional information about operation of GLC systems; Section
504 provides information about quantitation of residues.
See Section 205 for additional information about reference standards.
See Section 104 for additional information about reporting residues and determining
compliance with regulations.
See Section 105 for additional information about analytical limits of quantitation.
CONFIRMATION
After residues have been tentatively identified and quantitated by comparison to
appropriate reference standards, confirm identity according to principles discussed
in Section 103. Use appropriate tables of data (PESTDATA, tables accompanying
each method, Index to Methods) to choose most appropriate determinative steps.
Pesticide Analytical Manual Vol. ISECTION 304
304–34
Transmittal No. 2000-2 (11/1999)
Form FDA 2905a (6/92)
| 课件名称： | 美国FDA农残分析手册（第一巻英文） |
| 课件分类： | 化学 |
| 课件类型： | 电子图书 |
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- 1. 美国FDA农残分析手册（第一巻英文）：appndx1
- 2. 美国FDA农残分析手册（第一巻英文）：appndx2
- 3. 美国FDA农残分析手册（第一巻英文）：ch3tabs
- 4. 美国FDA农残分析手册（第一巻英文）：ch4tabs
- 5. 美国FDA农残分析手册（第一巻英文）：chapter1
- 6. 美国FDA农残分析手册（第一巻英文）：chapter2
- 7. 美国FDA农残分析手册（第一巻英文）：chapter3
- 8. 美国FDA农残分析手册（第一巻英文）：chapter4
- 9. 美国FDA农残分析手册（第一巻英文）：chapter5
- 10. 美国FDA农残分析手册（第一巻英文）：chapter6
- 11. 美国FDA农残分析手册（第一巻英文）：indices
- 12. 美国FDA农残分析手册（第一巻英文）：Introduction