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Anal Chem. 2012 Aug 7;84(15):6336-40.
Seo JH, Liu J, Fan X, Kurabayashi K.
Engineering Research Center for Wireless Integrated Microsensing and Systems, University of Michigan, Ann Arbor, Michigan 48109, USA.
Abstract
Microscale gas chromatography (uGC) is an emerging analytical technique for in situ analysis and on-site monitoring of volatile organic compounds (VOCs) in moderately complex mixtures. One of the critical subcomponents in a uGC system is a microfabricated preconcentrator (u-preconcentrator), which enables detection of compounds existing in indoor/ambient air at low (~sub ppb) concentrations by enhancing their signals. The prevailing notion is that elution peak broadening and tailing phenomena resulting from undesirable conditions of a microfabricated separation column (u-column) are the primary sources of poor chromatographic resolution. However, previous experimental results indicate that the resolution degradation still remains observed for a u-column integrated with other uGC subcomponents even after setting optimal separation conditions. In this work, we obtain the evidence that the unoptimized u-preconcentrator vapor release/injection performance significantly contributes to decrease the fidelity of uGC analysis using our state-of-the-art passive preconcentrator microdevice. The vapor release/injection performance is highly affected by the kinetics of the thermal desorption of compounds trapped in the microdevice. Decreasing the heating rate by 20% from the optimal rate of 90 °Cs(-1) causes a 340% increase in peak tailing as well as 70% peak broadening (30% peak height reduction) to the microscale vapor injection process.
