Gas chromatography
Chromatography is a technique for separating chemical substances that relies on differences in partitioning behaviour between a flowing mobile phase and a stationary phase to separate the components in a mixture.
HiQ graphics_ GC principle
The sample is carried by a moving gas stream through a tube packed with a finely divided solid or may be coated with a film of a liquid. Because of its simplicity, sensitivity, and effectiveness in separating components of mixtures, gas chromatography is one of the most important tools in chemistry. It is widely used for quantitative and qualitative analysis of mixtures, for the purification of compounds, and for the determination of such thermochemical constants as heats of solution and vaporization, vapour pressure and activity coefficients.