Performance evaluation of the Quick Test�, a colorimetric field method for the determination of pentachlorophenol in soil

Abstract

A novel colorimetric-based field test kit, the Quick Test®, has been developed by Envirol Inc. (North Logan, UT), for the quantitation of pentachlorophenol (PCP) in soil. The Quick Test differs from commercially available immunoassay field tests for PCP in that it is based on a photochemically induced oxidation–reduction reaction between PCP and a reagent that produces coloration proportional to concentration. Standard quality-control procedures were used to characterize the performance of the Quick Test and to test the suitability of this new method for field investigations of PCP-contaminated sites. A method detection limit of 1.5 mg/kg was achieved with a dynamic range up to 100 mg/kg, making this procedure of practical use at many PCP-contaminated sites. Accuracy and precision for the analysis of PCP in soils were comparable to laboratory standard methods that involve Soxhlet extractions and chromatographic quantitation. Because this is an oxidation–reduction reaction between halogenated molecules and the reagent, many, but not all, halogenated organic compounds will cause a response. An acid-base cleanup stop eliminates all but acidic halogenated compounds. The performance of the Quick Test in the field was compared with laboratory results. The statistical analyses performed to determine intermethod accuracy were linear regression analysis and the Wilcoxon Signed Ranks test. All data sets had r2 values greater than 0.915 and y-intercept values and the slope of the line that were not statistically different from 0 and 1, respectively, at a 90% confidence level. Data sets were not statistically different by the Wilcoxon test (95% confidence level), confirming the results from the regression analysis—that the Quick Test provided data equivalent (1:1) to the confirmatory methods. © 1998 John Wiley & Sons, Inc. Field Analyt Chem Technol 2: 29–37, 1998