Comprehensive GC GCxGC

The first column is generally a low polar capillary type with classical dimensions, 30 m X 0.25 mm x 0.25 jm, for instance. The second column is inevitably short (1 m, for example) because the elution time of the compounds of a given fracfion must not exceed a few seconds since the different trapped fractions follow each other in time intervals of the same order. The second column is generally of higher polarity than the first one. 

The chromatograms of GCxGC are radically different from those in traditional GC because the compounds are no longer represented by peaks but by stains in a 

FIGURE 1.10 GCxGC chromatogram of a crude oil distillation fraction. (Source Phillips, J. B. and J. Beens. 1999. J. Chromatogr. A 856 331-347. With permission.) 

This technique offers excellent chromatographic resolution and very low detection thresholds. It is generally coupled with mass spectrometry. Spectrometers using time-of-flight analyzers (refer to Chapter 4) are particularly efficient in this context. 

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