Online LC GC: The Ultimate "GC Connection"

Multidimensional chromatography is gaining in popularity for the analysis of extremely complex samples. In multidimensional chromatography, two or more columns are used, most often in tandem, to effect separations not possible with a single column. In this installment of "GC Connections," the ultimate connection, multidimensional chromatography with high performance liquid chromatography (HPLC) in the first dimension and gas chromatography (GC) in the second dimension, is discussed. On the surface, this seems simple: Just take a sample of the effluent from the HPLC instrument, and inject it into the GC system. However, several factors complicate this analysis, including solvent compatibility, separation time, and sample concentration. We begin by discussing the basic requirements for multidimensional separations, applied to the liquid chromatography gas chromatography (LC-GC) combination, followed by discussing some instrumental configurations that have been used for LC GC, and finish with some representative applications.