气相色谱Gas chromatography

由载气系统、进样口（分流/不分流，200–300 °C 汽化样品）、色谱柱（毛细管柱长 15–60 m、内径 0.25 mm，内壁涂聚二甲基硅氧烷或聚乙二醇等固定液）、柱温箱（可程序升温）和检测器组成。常用检测器：氢火焰离子化检测器（FID，对有机物灵敏、通用）、热导检测器（TCD，通用，可测无机气体）、电子捕获检测器（ECD，对含卤素化合物极灵敏）和质谱检测器。保留时间用于定性，峰面积用于定量。

A GC has a carrier-gas supply, an injector (split/splitless, vaporising the sample at 200–300 °C), a column (capillaries 15–60 m long and 0.25 mm across, coated with phases such as polydimethylsiloxane or polyethylene glycol), a programmable oven and a detector. Common detectors are the flame ionisation detector (FID, sensitive and universal for organics), the thermal conductivity detector (TCD, universal, including inorganic gases), the electron capture detector (ECD, extremely sensitive to halogenated compounds) and mass spectrometers. Retention time identifies and peak area quantifies.

1941 年马丁和辛格在提出液-液分配色谱时就预言可以用气体作流动相。1952 年英国的詹姆斯和马丁实现了气-液色谱，分离了脂肪酸。1958 年戈雷提出毛细管柱理论，1979 年惠普公司推出熔融石英毛细管柱，使分离效率大幅提高。

In proposing liquid–liquid partition chromatography in 1941, Martin and Synge predicted that a gas could serve as the mobile phase. In 1952 James and Martin in Britain achieved gas–liquid chromatography and separated fatty acids. Golay proposed the theory of capillary columns in 1958, and Hewlett-Packard's fused-silica capillaries of 1979 greatly raised efficiency.

GC 用于石油和天然气成分分析、香精香料、食品农药残留、环境挥发性有机物和多氯联苯、血液酒精浓度测定（顶空进样）、兴奋剂检测、药物残留溶剂检测和手性化合物对映体分析（手性柱）。不挥发或热不稳定的物质可先衍生化（如硅烷化、甲酯化）再分析。

GC analyses oil and gas, flavours and fragrances, pesticide residues in food, environmental volatile organics and PCBs, blood alcohol (by headspace sampling), doping agents, residual solvents in drugs and enantiomers on chiral columns. Non-volatile or heat-sensitive compounds can be derivatised first, for example by silylation or methylation.