SEDL / STP / STP1261-EB / STP15470S

A New Approach to Evaluating Pre-analysis Holding Times for the Determination of Volatile Organic Compounds in Soil

Hewitt, AD
Research physical scientist, U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH

Pages: 11    Published: Jan 1996

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Abstract

In the absence of volatilization losses, the short-term concentration stabilities of benzene, toluene, trans-1,2-dichloroethylene, and trichloroethylene were assessed in soil subsamples. Previous holding time studies for this matrix failed to eliminate volatilization as a variable, making them difficult to interpret. Here, vapor-fortified soil subsamples held in sealed glass ampoules for 14 days at 22°C experienced appreciable reductions in benzene and toluene concentrations, presumably attributable to biodegradation. When the same fortified soil was held as a subsample for either headspace or purge-and-trap analyses, it showed an appreciable reduction in toluene and a complete loss of benzene over a 14-day holding period at 4°C. In contrast, fortified soils held in sealed glass ampoules at 4°C, or dispersed in methanol and held at 22°C, showed no significant analyte losses over periods of 20 and 98 days, respectively.