Abstract
Two-dimensional (2D) gas chromatography (GC) provides enhanced vapor separation capabilities in contrast to conventional one-dimensional GC and is useful for the analysis of highly complex chemical samples. We developed a microfabricated flow-restricted pneumatic modulator (FRPM) for portable comprehensive 2D micro-GC (μGC), which enables rapid (2)D injection and separation without compromising the (1)D separation speed and eluent peak profiles. (2)D injection characteristics such as injection peak width and peak height were fully characterized by using flow-through micro-photoionization detectors (μPIDs) at the FRPM inlet and outlet. A (2)D injection peak width of ~25 ms could be achieved with a (2)D/(1)D flow rate ratio over 10. The FRPM was further integrated with a 0.5-m long (2)D μcolumn on the same chip, and its performance was characterized. Finally, we developed an automated portable comprehensive 2D μGC consisting of a 10 m OV-1 (1)D μcolumn, an integrated FRPM with a built-in 0.5 m polyethylene glycol (2)D μcolumn, and two μPIDs. Rapid separation of 40 volatile organic compounds in ~5 min was demonstrated. A hybrid 2D contour plot was constructed by using both (1)D and (2)D chromatograms obtained with the two μPIDs at the end of the (1)D and (2)D μcolumns, which was enabled by the presence of the flow resistor in the FRPM.