Site evaluation of field portable pentachlorophenol immunoassays

Abstract

Four pentachlorophenol (PCP) enzyme immunoassays for environmental analysis have been evaluated through the U. S. EPA Superfimd Innovative Technology Evaluation (SITE) program Three assays were formatted for on-site field use and one assay could be used in a field laboratory setting. The assays are designed to provide quick on-site results for either soil or aqueous matrices during the cleanup or characterization of hazardous waste sites. The principal intended use of the data is for screening purposes. Though assay performance was often lower than a developer's claim, the assays did generate results acceptable for many screening functions. A semi-quantitative immunoassay for PCP in soil failed to accurately classify samples into targeted concentration windows, but could screen samples into either high or low (e.g., > 50 mg/kg or < 0.5 mg/kg) concentration categories. A quantitative immunoassay applied to soil PCP analysis was biased low compared to GC/MS results; however, a concordance correlation coefficient of 0.938 (n = 114) for sample concentrations spanning 5 orders of magnitude shows the immunoassay was effective as a screening technology. Aqueous PCP immunoassays with analytical ranges of 3–40, 50–400, 0.1–10, and < 0.005 to > 5000 ug/kg were tested A microplate immunoassay for aqueous samples produced results 40% higher than GC/MS, but had similar variability. Three field kit immunoassays were biased high by 65 to 160% for aqueous PCP compared to GUMS and had larger variabilities. One field assay was found useful for screening at various concentration levels, but the other two appeared adequate only for classifying samples above or below the lower quantitative range limit. The findings emphasize the need to incorporate robust characteristics into field methods. A brief description of EPA's SITE program for evaluating new technologies such as immunoassays is also provided.