Applications of portable GC/purge-and-trap in field analysis
- Environmental Protection Agency, Athens, GA (United States)
A portable gas chromatograph (GC) was used to define the shallow and top of rock ground-water contamination plume at a site in North Carolina. The GC analyses enabled the engineer to design a cost-efficient and accurate system of permanent monitoring wells, instead of random placement. Historical data of this site indicated the presence of tetrachloroethene (PCE), with trichloroethene (TCE) and cis-1,2-dichloroethene (cis-1,2) as lesser constituents. The GC was equipped with a 30-meter fused silica/steel capillary column which completely resolved these analytes and a surrogate compound. The surrogate recovery provided immediate feedback on the analytical run and enhanced the on-site quality assurance objectives. A purge-and-trap accessory with carbon adsorbent was used for the analysis of the water samples. Field values agreed with conventional laboratory volatile analysis. Soil samples taken at the site were also analyzed with the GC using a modified aqueous extraction procedure. This consisted of using a portable balance to weigh 4-6 grams of soil into a standard 40 milliliter water vial followed by adding sufficient reagent water to eliminate headspace. After agitation for 15 seconds, an aliquot of the solution was analyzed as a water sample. Some false negative results from the traditional analytical methods were indicated when compared to the field generated data. Although in situ methods of collection and analysis of media would provide more representative values, this aqueous extraction of minimally disturbed soils proved simple, reliable and required no special equipment. Future plans include an expansion of the analyte list and a more exhaustive comparison of soil collection and analysis techniques.
- OSTI ID:
- 613802
- Report Number(s):
- CONF-970113-; TRN: 98:001739-0052
- Resource Relation:
- Conference: Field analytical methods for hazardous wastes and toxic chemicals conference, Las Vegas, NV (United States), 29-31 Jan 1997; Other Information: PBD: 1997; Related Information: Is Part Of Field analytical methods for hazardous wastes and toxic chemicals; PB: 909 p.
- Country of Publication:
- United States
- Language:
- English
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