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

A sensitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of the herbicide trifluralin. Polyclonal antibodies were develop ed in rabbits against a haptenic analogue N-(2,6-dinitro-4-trifluoromethylp henyl)-N-n-propyl-6-aminohexanoic acid. Using antibodies against this hapte n, a hapten-heterologous competitive ELISA in the antigen-immobilized forma t 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; isopropali n and pendimethalin did not show significant cross-reactivity. Various fact ors, 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 inc luding acetone. The optimized ELISA was found to be applicable to the detec tion of trifluralin in various matrices including surface water samples and vegetable juices. (C) 2000 Elsevier Science B.V. All rights reserved.