Development of an enzyme-linked immunosorbent assay (ELISA) for the herbicide trifluralin Original Research Article

A sensitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of the herbicide trifluralin. Polyclonal antibodies were developed in rabbits against a haptenic analogue N-(2,6-dinitro-4-trifluoromethylphenyl)-N-n-propyl-6-aminohexanoic acid. Using antibodies against this hapten, a hapten-heterologous competitive ELISA in the antigen-immobilized format allowed detection of the target analyte at concentrations between 0.1 and 100 ng ml−1. Closely related herbicides benfluralin, ethalfluralin cross-reacted with the antibodies in the optimized immunoassay at 5.2 and 2.9%, respectively, while less related dinitroaniline herbicides, e.g. isopropalin and pendimethalin did not show significant cross-reactivity. Various factors, e.g. the effect of pH and organic solvents have also been studied. The ELISA system tolerated methanol as a co-solvent at up to 5% content, while detection sensitivity appeared to be more vulnerable to other solvents including acetone. The optimized ELISA was found to be applicable to the detection of trifluralin in various matrices including surface water samples and vegetable juices.