Gas Chromatography (GC) explained

Gas Chromatography separates volatile and semi-volatile compounds that can be vaporised without decomposition. The sample is injected, swept by an inert carrier gas (helium, hydrogen or nitrogen) through a capillary column, and detected as components elute.

Key components

• Injector: split/splitless or on-column, vaporises the sample.
• Column: a coated fused-silica capillary inside a temperature-programmed oven.
• Detector: FID for general organics, TCD for fixed gases, ECD for halogenated compounds, or a mass spectrometer (GC-MS).

Typical applications

Petrochemical analysis, residual solvents in pharma, environmental volatiles, flavour and fragrance profiling. GC cannot analyse thermally labile or non-volatile analytes — those go to LC.