A dual-secondary column comprehensive twodimensional gas chromatograph for the analysis of volatile organic compound mixtures A comprehensive two-dimensional gas chromatograph has been developed that splits the primary column effluent into two secondary columns. The resulting technique, dual-secondary column comprehensive two-dimensional gas chromatography (GC62GC), produces a pair of two-dimensional chromatograms for each run. Differential flow modulation has been used to couple the primary column to the secondary columns. This study examines the use of a 6% cyanopropylphenyl, 94% dimethyl polysiloxane primary column, a polyethylene glycol secondary column, and a trifluoropropylmethyl polysiloxane secondary column. The polyethylene glycol column interacts strongly with compounds having high levels of hydrogen bond acidity, whereas the trifluoropropylmethyl polysiloxane secondary column interacts strongly with compounds having large dipole moments. A collection of 130 volatile organic compounds were analyzed using the GC62GC instrument. The data demonstrate that the dual secondary column configuration greatly facilitates compound identification and increases the separation efficiency of mixtures containing organic compounds with electronegative functional groups (e. g., alcohols, aldehydes, ketones, esters, etc.).