Chapter 8
Liquid Chromatograph
8.1 Introduction
High pressures
High speed
High performance
High sensitivity
8.2 Principles
Adsorption process
Xm + n Sa Xa + n Sm
(1)Liquid – Solid chromatography

nam
n
ma
SX
SX
K?
1.Classification
(2) Liquid – Liquid Chromatography
Partition Process
Xm Xs
kK
m
s
s
m
v
v
C
C

(3) Ion Exchange Chromatography
X+ + Y(resins) Y+ + X(resins)

r e s i nYX
Yr e s i nX
m
m
K
(4) Ion pair Chromatography


aa
K
-
O
-
YX
YX
X+a + Y- a X+ Y- org
2,Column efficiency of LLC
smmsdl HHHHHH
pl dH?2?
Eddy diffusion
u
DCH md
d?
Longitudinal diffusion
u
D
dC
H
u
D
dC
H
u
D
dC
H
m
psm
sm
m
pm
m
s
fs
s
2
2
2
Mass transfer
22
2
p
m
sm
m
m
f
s
s
md
p
d
D
C
D
C
d
D
C
C
DCB
dA
Cu
u
B
AH


H-U curve of GC and LC
3,Separation of Components
(1)Resolution R
)(5.0 21
1,2,
YY
ttR RR

(2)Separation Factor
1
2
1
2
1
2
1
2
'
'
'
'
V
V
t
t
k
k
K
K
7-19
7-20
4,Separation Equation of LC
Assume,Y1=Y2=Y,k1≈k2=k
2121216 kkRn
21216Rn e f f e c t
1141 k knR
7-21
7-22
8-23
5,Factors affect Resolution of a column
(1) Plat number n = f ( L,H )
H=f (u,k,Dm,Ds,….)
(3) Selectivity factor α= k2 / k1
(2) capacity factor k= p/q
P,q relay to mobile & stationary phase
mm uLt /?
kkttktt uLmRmR '),1(
,.,,),,,(,)1( mknk DkHLf
4,1 Yh
8.3 Instrumentation of LLC
1,LLS System
(1) Reservoirs (2) Pump
(3) Sample Injection Port
(4) Column (5) Detector
2,stationary phase
3,mobile phase (solvent)
Porous micro beads support
Pellicular micro beads support
Polarity order
N-Heptane < … < water
4,Gradient elution
5,Detector