Field Tests of a Microscale Gas Chromatograph for TCE Vapors at Parts-Per-Trillion Concentrations

Sun Kyu Kim, Hungwei Chang, Jonathan Bryant and Edward T. Zellers

Two fully integrated and automatically controlled MEMS gas chromatographs (µGC) were successfully deployed in the field to monitor trichloroethylene (TCE) at trace-level concentrations (0.6-80 ppb) in homes suffering from vapor intrusion (VI) from surrounding TCE-contaminated soil. Each instrument combines a high-volume sampling module (non-microfabricated) with a microanalytical module consisting of a microfocuser, dual microcolumns, and a chemiresistor array detector. A complete measurement cycle requires 15-35 min, depending on required sensitivity (sampling volume). A limit of detection of 0.04 ppb was achieved on the basis of field calibrations. Fixed-site (temporal TCE fluctuations) and portable (spatial mapping of TCE; see above) operating modes were successfully demonstrated. Stable responses and good agreement with concentrations determined with standard reference methods were achieved over a 2-week test period. This project is funded by the Department of Defense, Environmental Security Technology Crtification Program.