Gas Chromatography (GC) Tutorial
- Gas chromatography (GC) is also known as:
(i) gas-liquid chromatography (GLC)
(ii) vapor-phase chromatography (VPC)
(iii) gas-liquid partitition chromatography (GLPC)
- Gas chromatography can be used to separate volatile components in a mixture, that is, those components that vaporise without decomposing.
- Gas chromatographic column is composed of a mobile (moving) phase and stationary phase.
- Mobile phase (moving phase) is a carrier gas, usually an inert (unreactive) gas such as helium or nitrogen.
- Stationary phase is a liquid with a high boiling point adsorbed onto the surface of an inert solid such as glass.
- Components in a mixture are separated based on their ability to adsorb or bind to the stationary phase.
- The result of a gas chromatography experiment is a chart called a gas chromatogram (or chromatograph).
- The peaks on a gas chromatogram (gas chromatograph) occur at different positions and are of different areas:
(i) position of a peak is the compound's retention time, Rt, and can be used to identify the compound
(ii) area of a peak is related to the concentration of the compound in the sample mixture1
- The stationary phase, temperature, carrier gas and carrier gas flow rate are chosen to produce the best separation of components in the mixture.
- Retention time, Rt, is usually measured in minutes.
- Gas chromatography is used in the analysis of:
(a) air-borne pollutants
(b) performance enhancing drugs in athlete's urine samples
(c) oil spills
(d) essential oils in perfume preparation