An Enzyme-Linked Immunosorbent Assay (Elisa) for the Detection of Acetochlor

Abstract

Competitive enzyme-linked immunosorbent assays (ELISAs) were developed in hapten-homologous and hapten-heterologous formats for the detection of the chloroacetanilide herbicide acetochlor. ELISA systems were devised using antibodies generated against acetochlor conjugated to carrier proteins through a thioether moiety replacing the chlorine atom in the parent structure, while haptens modified both on the chloroacetyl moiety and on the ethoxymethyl group of acetochlor have been used for coating antigens. The optimized ELISA systems allowed the detection of acetochlor 0.2-65 µg/L, and cross-reactivity studies revealed high specificity of the immunoassay: only four (propisochlor, butachlor, alachlor and metolachlor) among 18 structurally related acetanilide herbicides, fungicides and intermediates showed significant (> 1%) cross-reactivity, with even the highest value (propisochlor) being below 10%. Assay performance was not affected detrimentally by methanol up to 10% (v/v) and ethanol up to 5% (v/v). Assay performance was tested by measuring acetochlor concentration in water samples and compared favorably ( r 2 = 0.976) with those detected by gas chromatographic method coupled with mass spectrometry (GC-MS) using solid-phase microextraction (SPME) for sample preparation.