GCxGC (“GC by GC”), also known as Comprehensive Two-Dimensional Gas Chromatography, is a powerful analytic technique that utilizes two columns of differing phase selectivity connected by a modulation device. The set-up of GCxGC improves peak capacity, resolution, and detectability. On average, a GCxGC analysis has five times the sensitivity and gains three times the number of compound identifications of typical GC-MS runs.
As a technique that has been around for over 25 years, some may argue that the technique has been over-hyped and a complicated research tool that doesn’t fit into routine analytical laboratories. However, several routine validated GCxGC methods have demonstrated that the technique is accurate, precise, and robust. Research has shown the benefits of GCxGC in a wide variety of applications (e.g. environmental, metabolomics, petroleum, food safety, fragrance). The benefits include increased peak capacity (i.e. resolution), structured two-dimensional chromatograms (i.e. contour plots), and sensitivity enhancement.
The merits of GCxGC as a separation science are clear, but how will it benefit a routine laboratory? Multiple analyte classes can be combined into a single analysis to save instrument and sample preparation time. Manual review time for non-target screening methods can be reduced with the increased peak resolution of a GCxGC analysis by creating a better library match leading to faster, more confident peak identification. Sample characterization is improved with a GCxGC analysis which increases confidence in decisions based on analytical results. The extra resolution afforded by the GCxGC analysis allows the use of more economical detectors, like the flame ionization detector (FID) or electron capture detector (ECD).