Chromatography Intro!

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Lecture 7

• Chromatography Intro!

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Solid Phase Extraction
Load (sample)
Eluent (solvent)
Compounds of interest stick to sorbent
Compounds of interest released from sorbent
Waste
Extract
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Chromatography
Mobile phase
Mobile phase
Load Sample (injection)
Compounds of interest in a plug
Differential interaction with stationary phase
separates compounds in time and space.
Detector
Detector
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Chromatography Definition
Separation of components in a mixture based on
the differential movement through a porous media
under the influence of a mobile phase
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First Chromatography Column
toluene
sample
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What happens in a chromatographic column?
Gas Chromatography (GC)
Liquid Chromatography (LC)
Distillation
Liquid-liquid extraction
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Theoretical Plate
GC - gas chromatography open tubular columns
Silica support
Stationary phase
Gas (mobile phase)
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Theoretical Plate
LC - liquid chromatography packed columns
Silica beads
Stationary phase
liquid (mobile phase)
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Number of Theoretical Plates
Length of the column
L
N
H
Height equivalent of a theoretical plate
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Retention Factor
Describes the strength of the interaction of a
compound with the stationary phase
tR-tM
VR-VM
k

tM
VM
1 lt k lt 10
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Solid Phase Extraction
Load (sample)
Eluent (solvent)
k lt 0.001
k gt 1000
Compounds of interest stick to sorbent
Compounds of interest released from sorbent
Waste
Extract
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Chromatography
Mobile phase
Mobile phase
Load Sample (injection)
1 lt k lt 10
Compounds of interest in a plug
Differential interaction with stationary phase
separates compounds in time and space.
Detector
Detector
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Retention Factor (k)
Describes the strength of the interaction of a
compound with the stationary phase
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Retention Factor (k)
Effect of k on Selectivity and Resolution in LC
Dong, M. Todays Chemist at Work. 2000, 9(2),
46-48.
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Selectivity
Describes differential mobility of 2 compounds
k2
K2

?
k1
K1
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Resolution
Describes how well 2 compounds are separated
2(tR2-tR1)
Rs
tw1tw2
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Resolution
Describes how well 2 compounds are separated
Rs
N1/2 (?-1)
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