What is gas chromatography and how does it work?

Gas chromatography (GC) separates and analyzes volatile compounds based on their distribution between a mobile phase (carrier gas - helium, nitrogen, hydrogen) and a stationary phase (column coating). Sample is vaporized, carried through the column where components separate based on boiling point and affinity to stationary phase. Separated components are detected (FID, TCD, MS) and produce chromatogram peaks. Retention time identifies compounds; peak area indicates concentration.