Gas Chromatography Introduction & Components of A Gas Chromatograph

What is Gas Chromatography?

Gas Chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition.

Introduction:

Gas chromatography (GC) is a widely used technique.Its applications, dating back to the 1940s, were essentially in the analyses of light fractions from petroleum refineries. The use of GC has grown due to its sensitivity, versatility, wide range of stationary phases, and speed with which new analyses can be developed. The technique has also gained great interest due to its case of automation. Because separation occurs in the gas phase, liquid and solid samples must first be vaporised.

This represents the main constraint of this technique; compounds that are analysed by GC have to be thermostable and sufficiently volatile. Usually the stationary phases used in GC are liquids; rarely solids. Applications of this technique are used in the fields of petrochemistry, pharmaceuticals, the environment flavour analyses and so on.

Components of A Gas Chromatograph:

The gas chromatograph is compound of several components. These components include the injector, the column and the detector.

 The mobile phase that transports the analytes through the column is a gas and is referred to as the carrier gas. The carrier gas flow, which is precisely controlled, allows great precision in the retention times.
The analysis starts when a small quantity of sample in liquid or gaseous state is injected. The dual role of the injector is to vapourise the analytes and to mix them uniformly in the mobile phase. Once the sample is vapourised in the mobile phase, it is swept into the column, which is usually a tube coiled into a very small section with the length that can very from 1 to 100 meters. The column containing the stationary phase is situated in variable temperature oven. At the end of the column, the mobile phase passes through a detector before it exits to the atmosphere. Some gaseous chromatograph models have their own power supply, permitting them to be used in the field. 



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