Retention multidimensional chromatography systems

Traditional gaseous fuel analysis is based on packed columns. Multidimensional chromatography, i.e. the use of columns with different retention characteristics coupled in series in one GC system, improves resolution of complex samples. But packed-column systems are not normally able to separate all compounds. To obtain more precise information about the composition of a gas sample, capillary columns were introduced in fuel analysis. The first were wall-coated open tubular (WCOT) columns with a nonpolar methylsilicone as stationary phase for hydrocarbon separation. However, the permanent gases were still separated in packed columns containing cross-linked polystyrene carbosieve, and molecular sieve as separation phases. 

The theoretical work that exploited the advantages of the multidimensional separation format appears to have been developed much later than the original experimental work. One of the earliest studies was conducted by Connors (1974), who assumed that the distribution of spots on a two-dimensional thin-layer chromatography (2DTLC) plate could be modeled using a Poisson distribution of data on each retention axis. He then constructed equations that related the number of chromatographic systems needed to resolve a specific number of compounds. One... 

Coupled column (multidimensional) systems in chromatography have also been developed to improve resolution. The coupled column procedure, as noted in Section 6.4, requires two or more columns of different kinds having different retention mechanisms. 

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