2DGC: When to Choose the Advanced Chromatography? CSIA data requires a good quality of chromatographic separation of the compounds of concern. For carbon and hydrogen applications in particular, incomplete GC separation results with a bias of the reported isotope results. For most groundwater applications, standard chromatography (utilizing separation on a single GC column) works well enough to assure good quality of the reported results.            KEI offers an advanced chromatography option (2D-GC) for samples where standard GC is inadequate. An outline of the method and typical scope of applications are available here. Examples of real-life samples analyzed by 2D-GC are provided here. Whereas 2D-GC is the only practical option for samples with strong matrix interferences, it can also benefit analysis of nominally "clean" samples with the analytes present near or below the reporting limits of methods using standard chromatography. In such samples, the use of 2D-GC decreases the baseline noise and permits better effective reporting limits.