Thermal desorption/injection characterization of a microfabricated passive preconcentrator/injector for micro gas chromatography

We have developed a microfabricated passive vapor preconcentrator/injector (μPPI) for field-deployable gas chromatographic (GC) analyses of volatile organic compozunds (VOCs). Interfaced with a properly configured microscale gas chromatograpy (GC) system, the device is designed to permit the analyses in a matter of minutes with high separation performance and detection sensitivity. Following diffusion-driven passive sample collection, the μPPI can be rapidly heated to thermally desorb the captured vapors and inject them with carrier gas to a downstream GC column and detector in a reusable manner for separation and quantification. To quantitatively predict the vapor desorption and injection performance of the device, theoretical models accounting for transient thermal energy transport, vapor desorption kinetics, and vapor flow fluid dynamics have been proposed and experimentally validated in this paper. Data obtained by preliminary tests using a conventional GC instrument are in agreement with model predictions, thus demonstrating the validity of the multi-physics approach used in our modeling study.