The effect of moisture and soil texture on pentachlorophenol immunoassay test kits

Environmental application of immunoassay testing, and the reason for its prevalence and popularity in the environmental field, is influenced by two major factors: time and money. Immunoassay methods are being used by environmental professionals as field screening methods in the site remediation process. Immunoassay methods have received regulatory approval and have been promulgated by the U.S. Environmental Protection Agency (U.S. EPA) in the 3rd edition (Update IIA) of Test Methods for Evaluating Solid Waste (SW-846). These methods generate semi-quantitative data which requires confirmation by a more rigorous analytical method.; As soil samples collected for field screening purposes seldom undergo the rigorous sample preparation procedures typically associated with laboratory analysis, there are numerous variables which may affect the field-generated sample results. The primary focus of this research was to examine the effect of soil moisture on the performance of immunoassay test kits for the determination of pentachlorophenol (PCP). It also examines the role that soil texture and various soil characteristics (percent clay, pH, organic matter) may have on immunoassay results. Three manufacturers' PCP in soil test kits were utilized for this research.; Moisture retention capacity was determined for each soil. Analyses were performed at various moisture levels for each soil type. Dry soils were included as a baseline. Soil preparation procedures included sample spiking with known concentrations of PCP. Replicates were added to evaluate reproducibility.; Results for Manufacturer 1 indicated that soil moisture level played a minimal role in the expected immunoassay results. Soil texture, especially clay content, played a more significant role in generating false positive results. Results for Manufacturer 2 indicated enhanced recovery for all samples at the low part per million (ppm) spike concentration. In addition, regardless of the soil texture, recoveries in excess of 100% were obtained for most of the moisture levels. In this case, it is unclear as to the role soil moisture plays. If anything, it appears to enhance PCP recovery with this test kit. Results for Manufacturer 3 were invalid as calibrators did not meet manufacturer recommended QC ranges.