Recent advances in flow-controlled multidimensional gas chromatography
The continued development of flow-controlled two-dimensional gas chromatography (2-D GC) is reviewed, with a special emphasis on results published from 2001 through 2011. Heart-cutting 2-D GC continues to be used for isolating selected components in complex mixtures. The programmable and highly precise flows and temperatures produced by modern gas chromatographs have made it easier to selectively transfer analytes to the secondary column and to backflush unwanted components from the primary column. Several new Deans switch interfaces for performing heart-cutting 2-D GC have been introduced, with most attention given to devices that integrate the flow connections into a single unit. Heart-cutting 2-D GC has been used to isolate analytes in a wide variety of complex mixtures including fuels, industrial feedstocks, fragrances, and environmental extracts. Valve-based comprehensive 2-D GC (GC × GC) was also actively developed in the past decade. Valve-based modulation is a simple way to generate GC × GC separations without using cryogenic fluids. More than ten new valve-based modulators were introduced. Diaphragm valves fitted with sample loops are the most common low duty cycle modulators, whereas fluidic modulators that employ differential flow conditions are the most common high duty cycle modulators. Applications of valve-based GC × GC include analysis of hydrocarbon mixtures, essential oils, and environmental samples. âº The last 10 years of developments in heart-cutting 2-D GC and valve-based GC × GC are reviewed. âº The operating principles of several new devices for conducting heart-cutting 2-D GC are examined. âº Modulators for conducting valve-based GC × GC separations are described and evaluated. âº The published applications of heart-cutting 2-D GC and valve-based GC × GC are summarized.