Comprehensive two-dimensional gas chromatography using a MEMS thermal modulator

This paper presents the first comprehensive two-dimensional gas chromatographic (GC×GC) separations of volatile organic compound (VOC) mixtures employing a microfabricated mid-point thermal modulator (μTM). The first-dimension column was coated with a non-polar polydimethylsiloxane (PDMS) film and the second-dimension column was coated with the polar polyethylene glycol (PEG) film. μTM heating and cooling rates of 2400 ° C/s and -168 °C/s, respectively, were achieved. The effects of system flow rate and the maximum and minimum μTM temperatures on the resolution and signal enhancement are explored with small sets of 5-7 VOCs for a fixed modulation period of 6 s. A structured 2-D chromatogram is produced and a 15-VOC GC×GC separation is achieved in 185 sec. This low-power, consumable-free μTM provides performance rivaling many commercial macroscale thermal modulators.