Development and validation of an ELISA for metolachlor mercapturate in urine

The National Institute for Occupational Safety and Health (NIOSH) has condu cted an exposure assessment study of herbicide applicators exposed to numer ous commercial acetanilide-containing products. An enzyme-linked immunosorb ant assay (ELISA) was developed to measure the putative major human metabol ite of one of these, metolachlor mercapturate (MM). Antibodies were obtaine d by immunizing rabbits with a keyhole limpet hemocyanin (KLH) MM conjugate and the sera used as a source of IgG antibodies for the ELISA development. The percent cross-reactivities for metolachlor (ME), acetochlor mercaptura te (ACM), alachlor mercapturate (AM) and alachlor (AL) were 39 and 23, resp ectively. Cross-reactivity for alachlor mercapturate (AM) and alachlor (AL) are not given as 50% inhibition was not observed for the highest concentra tion tested. Percent inhibitions at 20 mu g l(-1) for MM, ME, ACM, AM and A L were 20, 29, 48, 72 and 90, respectively. The measured least detectable d ose (LDD) of metolachlor mercapturate was 0.18 mu g l(-1). Inter-assay conc ordance was <15%. These data indicate that the MM ELISA developed in this s tudy may be used to estimate body burdens of ME from urinary metabolites of herbicide applicators. (C) 1999 Elsevier Science B.V. All rights reserved.