Gas chromatography: the sample is driven by gas as mobile phase, separated by chromatographic column, and the signal is obtained in the detector.

Liquid chromatography: the sample is driven by liquid as mobile phase, and the signal is obtained in the detector after separation by chromatographic column.

Simply put, the gas phase is like the wind blowing sand, with fine sand first and coarse sand later.

The liquid phase is like running water washing stones. Small stones first, then big stones. (This is not very rigorous, just for understanding)

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Gas chromatography: used for the separation and determination of samples with small molecular weight and easy gasification, such as carbon dioxide, chloroform, methanol, gasoline, kerosene, lipids, organophosphorus pesticides, organochlorine pesticides, food additives, etc.

Liquid chromatography: separation and determination of high molecular weight soluble samples, such as chloramphenicol, oxytetracycline and other drugs, pesticides, amino acids, disinfectants, etc.

Gas phase analysis accounts for 30% of analyzable compounds, and liquid phase analysis accounts for 70% of analyzable compounds.