chapter 8 liquid chromatograph
TRANSCRIPT
LOGOChapter 8 Liquid Chromatograph Chapter 8 Liquid Chromatograph
8.1 Introduction
High pressures
High speed
High performance
High sensitivity
LOGO8.2 Principles8.2 Principles
Adsorption process
Xm + n Sa Xa + n Sm
(1)Liquid – Solid chromatography
nam
nma
SX
SXK
1.Classification
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(2) Liquid – Liquid Chromatography
Partition Process
Xm Xs
kKm
s
s
m
v
v
C
C
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(3) Ion Exchange Chromatography
X+ + Y(resins) Y+ + X(resins)
resinYX
YresinX
m
m
K
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(4) Ion pair Chromatography
aa
K-
O-
YX
YX
X+a + Y-
a X+ Y-
org
LOGO2. Column efficiency of LLC2. Column efficiency of LLC
smmsdl HHHHHH
pl dH 2Eddy diffusion
u
DCH md
d
Longitudinal diffusion
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uD
dCH
uD
dCH
uD
dCH
m
psmsm
m
pmm
s
fss
2
2
2
Mass transfer
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22
2
pm
sm
m
mf
s
s
md
p
dD
C
D
Cd
D
CC
DCB
dA
Cuu
BAH
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H-U curve of GC and LC
LOGO3. Separation of Components3. 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
LOGO4. Separation Equation of LC4. Separation Equation of LC
Assume: Y1=Y2=Y, k1≈k2=k
212
1216 k
kRn
2
1216
Rneffect
11
41
k
knR
7-21
7-22
8-23
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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
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mm uLt /
kkttkttuL
mRmR '),1(
,...),,,(,)1( mk
nk DkHLf
4,1 Yh
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8.3 Instrumentation of LLC
1. LLS System
(1) Reservoirs (2) Pump
(3) Sample Injection Port
(4) Column (5) Detector
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2. stationary phase
3. mobile phase (solvent)
Porous micro beads support
Pellicular micro beads support
Polarity order
N-Heptane < … < water
LOGO4. Gradient elution
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5. Detector