Laboratory and field screening strategies for measuring volatile organic compounds in landfill gas

Distinct patterns often exist in the presence and absence of hazardous cont aminants in the environment. These patterns can be used to select efficient screening tools, or groups of compounds that provide the most information on overall occurrences of a larger target group of compounds. By using thes e screens to indicate whether a sample is contaminated with detectable amou nts of the compounds of interest, attention can be focused on those samples considered most likely to contain measurable concentrations of targeted co mpounds. The cost savings that result from eliminating samples that are mos t likely uncontaminated can be applied to obtaining additional samples that more accurately characterize the spatial or temporal variability of the en vironmental problem. In a retrospective application of screening techniques to the State of California's database of volatile organic compounds in lan dfill gas, two laboratory screening compounds, perchloroethylene and methyl ene chloride, represent over 95% of the total number of positive detections of a target group of 10 volatile organic compounds. Benzene and vinyl chlo ride, two field screening compounds that were selected using the characteri stics of commercially available colorimetric detector tubes, recorded 74% o f the total contaminant detections and a 52% saving in analytical costs as compared to an exhaustive analysis of every sample for all 10 volatile orga nic compounds. The number of detections recorded could have been improved i f more sensitive and less selective field screening devices were available. (C) 1999 Academic Press.