Preparative Gas Chromatography (Prep-GC)

Abstract

Differentiating structural isomers using gas chromatography (GC) and mass spectrometry (MS) can be difficult and often further structural elucidation is required. This is also the case when new or unknown compounds need to be identified in complex organic mixtures. Once sufficient amounts of the desired compound are obtained, structural elucidation can be determined by using additional analytic techniques, such as nuclear magnetic resonance, Fourier transform infrared spectroscopy, x-ray crystallography, and accelerator mass spectrometry. In these cases, preparative-GC (prep) or preparative multidimensional gas chromatography, suitably designed with necessary trapping and heart-cutting devices in a conventional GC, can be used to isolate a single compound. This is achieved by the use of either a single collector or multiple collectors with flow switching that allows multiple component isolation. The amount of analyte collected can be increased with multiple injections, thus ensuring that the analyte obtained is of sufficient purity and collected in a quantity that allows for structural characterization. This article outlines approaches to the preparative technique and provides selected illustrative applications.