GAS LIQUID CHROMATOGRAPHY

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GAS LIQUID CHROMATOGRAPHY
Principles Partition of molecules between gas
(mobile phase) and liquid (stationary phase).
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Most Common Stationary Phases

• 1. Separation of mixture of polar compounds
• Carbowax 20M (polyethylene glycol)
• 2. Separation of mixtures of non-polar compounds
• OV101 or SE-30 (polymer of methylsilicone)
• Methylester of fatty acids
• DEGS (diethylene glycol succinate)

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Gas Chromatography
Filters/Traps
Data system
Syringe/Sampler
Regulators
Inlets
Detectors

• gas system
• inlet
• column
• detector
• data system

Column
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Schematic Diagram of Gas Chromatography
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Thermal Conductivity Detector
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Thermal Conductivity Detector
When a compound elutes, the thermal conductivity
of the gaseous mixture of carrier gas and
compound gas is lowered, and the filament in the
sample column becomes hotter than the other
control column. Its resistance increased, and
this imbalance between control and sample
filament resistances is measured by a simple
gadget and a signal is recorded
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Relative Thermal Conductivity
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Gas Chromatography Application
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SEMI- QUANTITATIVE ANALYSIS OF FATTY ACIDS
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TENTATIVE IDENTIFICATION OF UNKNOWN COMPOUNDS
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Retention Times
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GLC ADVANTAGES
1. Very good separation 2. Time (analysis is
short) 3. Small sample is needed - ml 4. Good
detection system 5. Quantitatively analyzed