A low power, high-speed miniaturized thermal modulator for comprehensive 2D gas chromatography

In comprehensive two-dimensional gas chromatography (GC×GC), a modulator is placed at the juncture between two separation columns to focus and re-inject eluting mixture components, and thereby enhance the selectivity, sensitivity, and analyte capacity. Here, we present the design, fabrication, and testing of a two-stage microscale thermal modulator (¿TM). The ¿¿ cryogenically trap analytes eluting from the first column and thermally inject them into the second column. For this operation, each stage is periodically heated to 200°C for 100 ms and then cooled to -50°C for a few second. Preliminary results using a conventional capillary column interfaced to the ¿TM demonstrate successful modulation of a mixture of alkanes with a sensitivity enhancement as high as 24 folds.