Sample preparation for gas chromatography

Abstract Direct injection is suitable for the analysis of simple mixtures of thermally stable compounds with similar physical and chemical properties and a limited relative concentration range. For most other samples, some form of sample preparation is required. Typical methods include distillation, solvent extraction, liquid–liquid extraction, solid-phase extraction, microextraction, and derivatization. A combination of techniques is often required to prepare a complex sample. A typical scheme for sample preparation might include one or all of the following steps: preliminary sample fractionation; isolation of the target compounds of interest; and concentration to a level suitable for detection. In this way, the sample introduced into the gas chromatograph will be effectively separated with a suitable separation time, with an adequate detector response, and without significant column contamination.