Multidimensional gas chromatography with parallel cryogenic traps

In its most common form, multidimensional gas chromatography (MDGC) has been restricted to use of a single intermediate cryogenic trap between two serially coupled columns. This paper describes successful implementation of a multi-port valve MDGC system with two parallel cryogenic traps interposed between a first stage GC precolumn and a second stage GC analytical column. Using this strategy, it is possible to accommodate the constraints of infrared and mass spectrometry detectors in a directly linked structure elucidation system. Analysis of an unleaded gasoline sample serves to demonstrate the analytical advantages. Following a preliminary separation, using only the first column, a second portion of the same sample is injected for GC-GC analysis. Heart cuts from four different segments of the chromatogram identified in the preliminary separation are analyzed using an analytical column of different selectivity. The preliminary single-stage separation of the four chromatogram areas contained 7, 3, 12, and 12 peaks for cuts A, B, C, and D respectively, for a total of 34 peaks. The second stage separation of heart cuts A, B, C, and D yields 16, 17, 30, and 30 peaks, totaling 93 peaks. These results demonstrate significantly enhanced chromatographic resolution using chromatographic conditions permitting joint use of informationrich infrared and mass spectral detectors. Thus, it is suggested that MDGC systems employing more than two parallel cryogenic traps and multiple analytical GC columns could be useful.
A method for the complete qualitative analysis of a complex mixture is presented. This involves the utilization of parallel cryogenic traps in multidimensional gas chromatographic (MDGC) separation system. An unleaded gasoline sample was used to test the method. Chromatographic resolution of the sample was significantly enhanced by the combination of infrared and mass spectral detectors. The utility of the MDGC system innovation was demonstrated.