An Enzyme-linked Immunosorbent Assay for the Detection of Bifenthrin

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed for the quantitative detection of bifenthrin. Two haptens, LBc ((2-methyl[1,1′-biphenyl]-3-methoxy) carbonyl propionic acid) carbonyl propionic acid) and LBy ((2-methyl[1,1′-biphenyl]-3-yl)carboxylic acid), were synthesized from 2-methyl-3-phenylbenzyl alcohol, a metabolite of bifenthrin. The LBc was conjugated to bovine serum albumin (BSA) for the immunogen by the carbodiimide method, and the LBc and LBy were conjugated to ovalbumin (OVA), respectively, for the coating antigens by the mixed anhydride method. Polyclonal antibodies was raised against LBc-BSA conjugate in rabbits and hapten-OVA conjugates as coating antigens were screened and selected for the assay in the homologous and heterologous ELISA systems, and the titers of antiserum (5.12 × 104) were determined by non-competitive ELISA procedure. Under the optimum assay conditions of pH 7.5, PBS of 0.3 M Na+ and 30% methanol, the heterologous assay system was more sensitive. The IC50 value for bifenthrin was (2.16 ± 0.32) mg l−1, and the detection limit was (0.016 ± 0.002) mg l−1. Pyrethroids, such as cyhalothrin, deltamethrin, cypermethrin, fenvalerate, fenpropathrin, and pyrethroid metabolite, 3-phenoxybenzoic acid, did not cross-react significantly in this assay.