Evaluation of Microtiter-Plate Enzyme-Linked Immunosorbent Assay for the Analysis of Triazine and Chloroacetanilide Herbicides in Rainfall

Abstract

Triazine and chloroacetanilide concentrations in rainfall samples collected from a 23-state region of the United States were analyzed with microtiter-plate enzyme-linked immunosorbent assay (ELISA). Thirty-six percent of rainfall sample (2072 out of 5691) were confirmed using gas chromatography/mass spectrometry (GC/MS) to evaluate the operating performance of ELISA as a screening test. Comparison of ELISA to GC/MS results showed that the two ELISA methods accurately reported GC/MS results (m = 1), but with more variability evident with the triazine than with the chloroacetanilide ELISA. Bayes's rule, a standardized method to report the results of screening tests, indicated that the two ELISA methods yielded comparable predictive values (80%), but the triazine ELISA yielded a false-positive rate of 11.8% and the chloroacetanilide ELISA yielded a false-negative rate of 23.1%. The false-positive rate for the triazine ELISA may arise from cross reactivity with an unknown triazine or metabolite. The false-negative rate of the chloroacetanilide ELISA probably resulted from a combination of low sensitivity at the reporting limit of 0.15 Îg/L and a distribution characterized by 75% of the samples at or below the reporting limit of 0.15 Îg/L.

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Pomes, M.L., Thurman, E.M., Aga, D.S., and Goolsby, D.A., 1998, Evaluation of microtiter-plate enzyme-linked immunosorbent assay for the analysis of triazine and chloroacetanilide herbicides in rainfall: Environmental Science & Technology, v. 32, p. 163-168.

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