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IMMUNOASSAY FOR P-NITROPHENOL IN URINE
Citation:
Rogers, K. AND J. Emon. IMMUNOASSAY FOR P-NITROPHENOL IN URINE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-93/074 (NTIS PB93175552).
Description:
Urinary excretion of nitrophenol metabolites is an important index of human exposure to organophosphate pesticides. In particular, p-nitrophenol, a major urinary metabolite of parathion, can be used as a biomarker of human exposure. Immunoassay methods have been recently described for detection of p-nitrophenol (Q.X. Li et al.,J. Agric. Food Chem., 1991, 39, 1685-1692). In the present paper, the effects of a urine matrix on Lhe detection of p-nitrophenol are reported using both fluorescence and absorbance-based ELISAs. A competition format using the enzyme-amplified catalysis of 4-nitro-phenyl phosphate or 4-methylumbelliferyl phosphate was used to report the analyte con:entration. The presence of urine during the antibody-analyte interaction inhibited )roduct formation in the final step of the assay and shifted the inhibition curves to the right, increasing the apparent I50 values for p-nitrophenol. The various urine samples collected from volunteers, not occupationally exposed to parathion, varied in their ability to inhibit color information and increase I50 values.