Characterization of gaseous mixtures of organic compounds with dual-secondary column comprehensive two-dimensional gas chromatography (GC x 2GC)

A comprehensive two-dimensional gas chromatograph with dual secondary columns (GC x 2 GC) was used to characterize gaseous mixtures of volatile organic compounds (VOCs). Samples were collected on multi-layer sorbent tubes and introduced into the gas chromatograph using a thermal desorption apparatus. Differential flow modulation was used to couple the primary column to the secondary columns. Each GC x 2GC analysis produced a pair of two-dimensional gas chromatograms. The chromatograms provided complementary information due to the unique selectivities of the secondary columns. The additional information was especially useful in separating and identifying oxygenated and aromatic compounds. Samples of outdoor air, indoor air, and exhaled breath were analyzed with the GC x 2 GC system. More than 100 volatile organic compounds could be separated in less than 10 minutes. The identities of approximately 50 peaks were determined for each sample.