Comprehensive two dimensional high-speed gas chromatography with chemometric analysis

High-speed comprehensive two-dimensional gas chromatography (GCxGC) is performed, in which a polar second column performs separations every half second on portions of the effluent from a nonpolar first column. Chemometric techniques that are traditionally used on chromatographic separations with multichannel detection are applied to two-dimensional chromatographic data, for the purpose of quantifying incompletely resolved peaks. Generalized rank annihilation method (GRAM) is evaluated in the quantiftcation of varying amounts of selected overlapped analytes in a GCxGC analysis of modified white gasoline. GRAM requires a sample and standard data set for quantification, and the high retention time precision arising from use of shortened GC columns aids in the analysis. Results from GRAM analysis of GCxGC data are compared with a reference GC method. The test analytes ethylbenzene and m-xylene, existing in various proportions in white gasoline samples, were successfully deconvoluted despite having resolutions of 0.46 and 0.20 on the first and second dimensions of separation, respectively. Like other second-order techniques, GRAM was able to reliably quantify m-xylene despite the presence in the analytical sample of an overlapping compound not present in the calibration standard. Because GRAM can be successfully applied to GCxGC data, full resolution of all the analytes of interest is not necessary. As a result, GCxGC run times can be dramatically shortened, which has significant implications for analyses in which short cycle times are critical, such as in process analysis.