A comparison of modulating interface technologies in comprehensive two-dimensional gas chromatography (GC × GC)

Comprehensive two-dimensional gas chromatography (GC × GC) is a multidimensional method where the entire sample of interest undergoes chromatographic analysis via orthogonal coupling of two serially connected capillary columns, with selectivities of each dimension both independent and unique. The method of transferring the fraction eluting from the primary column onto the head of the secondary column for subsequent analysis is critical to the success of the technique. A number of devices are employed for this role. This paper compares both mechanical and nonmechanical thermal modulation interfaces for GC × GC. A simple, robust method is required for the routine analysis of substituted aromatic compounds in urban air, and a comparison is made between simple low cost ohmically heated capillaries, cryogenic modulators, and heated sweepers for this purpose. The relative chromatographic resolution, technical ease, and cost effectiveness of each technique are discussed.