title: Microfabricated gas chromatograph for on-site determinations of TCE in indoor air arising from vapor intrusion. 2. Spatial/temporal monitoring.
abstract: We demonstrate the use of two prototype Si-microfabricated gas chromatographs (μGC) for continuous, short-term measurements of indoor trichloroethylene (TCE) vapor concentrations related to the investigation of TCE vapor intrusion (VI) in two houses. In the first house, with documented TCE VI, temporal variations in TCE air concentrations were monitored continuously for up to 48 h near the primary VI entry location under different levels of induced differential pressure (relative to the subslab). Concentrations ranged from 0.23 to 27 ppb by volume (1.2-150 μg/m(3)), and concentration trends agreed closely with those determined from concurrent reference samples. The sensitivity and temporal resolution of the measurements were sufficiently high to detect transient fluctuations in concentration resulting from short-term changes in variables affecting the extent of VI. Spatial monitoring showed a decreasing TCE concentration gradient with increasing distance from the primary VI entry location. In the second house, with no TCE VI, spatial profiles derived from the μGC prototype data revealed an intentionally hidden source of TCE within a closet, demonstrating the capability for locating non-VI sources. Concentrations measured in this house ranged from 0.51 to 56 ppb (2.7-300 μg/m(3)), in good agreement with reference method values. This first field demonstration of μGC technology for automated, near-real-time, selective VOC monitoring at low- or subppb levels augurs well for its use in short- and long-term on-site analysis of indoor air in support of VI assessments.
authors.affiliation: Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109-2029, United States.
authors.forename: Sun Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: David R
authors.initials: DR
authors.lastname: Burris
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bryant-Genevier
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Gorder
authors.forename: Erik M
authors.initials: EM
authors.lastname: Dettenmaier
authors.forename: Edward T
authors.initials: ET
authors.lastname: Zellers
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D002849:Chromatography, Gas / Q000295:instrumentation*; D055616:Microtechnology / Q000295:instrumentation*; D013997:Time Factors; D014241:Trichloroethylene / Q000032:analysis*; D014589:Utah; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D014241:Trichloroethylene