DEVELOPMENT OF A CLASS-SPECIFIC COMPETITIVE ELISA FOR THE BENZOYLPHENYLUREA INSECTICIDES

A competitive enzyme-linked immunosorbert assay (ELISA) was developed for the quantitative detection of five benzophenylurea insecticides in soil (90% methanol extraction) and water. No significant matrix effec ts were observed. Conjugates of diflubenzuron derivatives with protein s were prepared by attachment at either the urea nitrogen of diflubenz uron or the 4-position of the aniline ring, wherein bridging groups of various lengths were used between the hapten and the protein carrier. All combinations of antiserum to each immunogen and enzyme tracer wer e examined, and an assay was developed using an antibody developed to a hapten conjugate coupled through a succinyl chain at the 4-aniline p osition. The assay gave 50% inhibition of antibody binding (IC50) at 0 .6 ppb for diflubenzuron, 5 ppb for teflubenzuron, 10 ppb for flufenox uron, 31 ppb for lufenuron, and 45 ppb for chlorfluazuron, with detect ion limits in the range of 0.05-2.3 ppb for these compounds. The basis for the superior cross-reaction of diflubenzuron was examined by mole cular modeling, which suggested that the planarity of the molecules, e lectron-withdrawing groups, and steric effects of chlorines attached t o the phenyl ring may be critical factors affecting antibody binding.