Clor-n-soil Pcb Test Kit, Dexsil Corp. Innovative Technology Evaluation Report National Risk Management Research Laboratory Office of Research and Development U.s. Environmental Protection Agency

This innovative technology evaluation report (ITER) presents the evaluation of two field screening technologies for determining polychlorinated biphenyl (PCB) contamination in soil. The demonstration was conducted by PRC Environmental Management, Inc. (PRC), under contract to the Environmental Protection Agency’s (EPA) Environmental Monitoring Systems Laboratory-Las Vegas (EMSL-LV). The Clor-N-Soil Test Kit and the L2000 PCB/Chloride Analyzer, both developed by the Dexsil Corporation, were demonstrated in August 1992 in Kansas City, Missouri. The Clor-N-Soil Test Kit is designed to provide semiquantitative results for PCBs in soil. It provides a greater than or less than 50 milligrams per kilogram (mg/kg) result. Compounds containing organic chlorine, such as PCBs, are extracted from the soil samples; through a series of chemical steps, the chloride ions are stripped from the compound, transferred to an aqueous solution, and mixed with a reagent to induce a color change. Because the test kit reacts to all sources of organic chlorine, the presence of some compounds other, than PCBs will cause it to produce false positive results. The presence of sulfur in samples may produce the same result. During this demonstration, the test kit produced 87 correct assays, 58 false positives, and 1 false negative. Because the test kit reacts with the chlorine in PCBs, it will produce different responses to individual Aroclors, each of which contains a different percentage of chlorine. The test kit will produce false negative results for samples containing Aroclors 1016, 1221, and 1232, which contain lower percentages of chlorine than Aroclor 1260, the Aroclor the kit is designed to detect. Like the Clor-N-Soil Test Kit, the L2000 PCB/Chloride Analyzer uses the principle of total organic chlorine detection. The analyzer, though, uses a chloride-specific electrode to measure the amount of total organic chlorine in the extract. The analyzer also is capable of electronically converting the chloride concentration to produce quantitative results for two different Aroclors. The detection limit of the analyzer is reported to be 5 mg/kg, although a detection limit of 2 mg/kg was used during this demonstration. Because the analyzer reacts with the chlorine in PCBs, it will produce various responses to individual Aroclors. The analyzer has a high likelihood of producing false negative results for samples containing Aroclors 1016, 1221, and 1232, which contain lower percentages of chlorine than the Aroclors the analyzer is set to detect. If, however, the Aroclor type is known prior to analysis, the analyzer can be set to “total chlorine” and the result divided by the appropriate factor (0.21 for Aroclor 1221, 0.32 for Aroclor 1232, and so forth.) During this demonstration the analyzer’s precision was found to be acceptable after reviewing its performance on duplicate samples. To assess its accuracy, PRC used a linear regression approach to compare the analyzer’s data to corresponding confirmatory laboratory data. This analysis was based on 47 matched pairs of positive sample results. For this regression analysis, the 3 factor was 0.86, indicating that a relationship existed between the two data sets. The analysis defined a regression line with a y-intercept of 26.6 mg/kg and a slope of 0.84. These results indicate that the analyzer is not accurate, but can be corrected mathematically. This report was submitted in fulfillment of contract No. 68-CO-0047 by PRC, under sponsorship of the EPA. This report covers a period from February 10, 1992, to August 31, 1992, and work was completed as of February 28, 1993.