Title: | A micro passive preconcentrator for micro gas chromatography |
Author(s): | Zhan C; Akbar M; Hower R; Nunovero N; Potkay JA; Zellers ET; |
Address: | "Department of Environental Health Sciences, University of Michigan, Ann Arbor, MI, USA. ezellers@umich.edu" |
ISSN/ISBN: | 1364-5528 (Electronic) 0003-2654 (Linking) |
Abstract: | "We describe a microfabricated passive preconcentrator (muPP) intended for integration into gas chromatographic microsystems (muGC) for analyzing volatile/semi-volatile organic compounds (S/VOC). Devices (8 x 8 mm) were made from a silicon-on-insulator top layer and a glass bottom layer. The top layer has 237 apertures (47 x 47 mum) distributed around the periphery of a circular region (5.2 mm o.d.) through which ambient vapors diffuse at predictable rates. Two internal annular cavities offset from the apertures are packed with approximately 800 mug each of commercial carbon adsorbents. Thin-film heaters thermally desorb captured vapors, which are drawn by a pump through a central exit port to a micro injector for analysis with a bench scale GC. The 15 test compounds spanned a vapor pressure range of 0.033 to 1.1 kPa. Effective (diffusional) muPP sampling rates ranged from 0.16 to 0.78 mL min-1 for short-duration exposures to approximately mg m-3 vapor concentrations. Observed and modeled sampling rates generally agreed within 15%. Sampling rates for two representative compounds declined by =30% between 0.25 and 24 h of continuous exposure. For one of these, the sampling rate declined by only 8% over a approximately 2300-fold concentration range (0.25 h samples). Desorption (transfer) efficiencies were >95% for most compounds (250-275 degrees C, 60 s, 5 mL min-1). Sampling rates for mixtures matched those for the individual compounds. Dissipating no energy while sampling, additional advantages of this novel device include short- or long-term sampling, high capacity and transfer efficiency for a diverse set of S/VOCs, low transfer flow rate, and a robust fabrication process" |
Notes: | "PubMed-not-MEDLINEZhan, Changhua Akbar, Muhammad Hower, Robert Nunovero, Nicolas Potkay, Joseph A Zellers, Edward T eng England 2020/09/24 Analyst. 2020 Nov 23; 145(23):7582-7594. doi: 10.1039/d0an01485k" |