Development of a Class-Specific Competitive ELISA for the Benzoylphenylurea Insecticides

Abstract

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 effects were observed. Conjugates of diflubenzuron derivatives with proteins were prepared by attachment at either the urea nitrogen of diflubenzuron 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 were examined, and an assay was developed using an antibody developed to a hapten conjugate coupled through a succinyl chain at the 4-aniline position. The assay gave 50% inhibition of antibody binding (IC 50 ) at 0.6 ppb for diflubenzuron, 5 ppb for teflubenzuron, 10 ppb for flufenoxuron, 31 ppb for lufenuron, and 45 ppb for chlorfluazuron, with detection 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 molecular modeling, which suggested that the planarity of the molecules, electron-withdrawing groups, and steric effects of chlorines attached to the phenyl ring may be critical factors affecting antibody binding.

Atypical antibody specificity: advancing the development of a generic assay for sulphonamides using heterologous ELISA

“…It is well established that immunoassays for small molecules using different but analogous haptens and alternative conjugation strategies can improve the assay performance in sensitivity and/or speci®city. 29,30 Thomson and Sporns 31 improved the detection limits of an assay for STZ by optimising the hapten/protein ratios and enzyme substrates used in the assay. In the study reported here, the number of drugs that could be measured by R451 increased when using a heterologous coating conjugate.…”

“…The need to consider both the structure of the hapten as well as competitors and linkers is obvious from the considerable amounts of literature available. 22,29,30,34,35 In all cases, assay speci®city and/or sensitivity have been manipulated by careful hapten design. Selection of the location of linkage to carrier molecules is vital, since it is often necessary to avoid using functional groups that form the character of the molecule, hence selection of the R-group for linkage in this case.…”

Competitive immunoassay by capillary electrophoresis with laser‐induced fluorescence for the trace detection of chloramphenicol in animal‐derived foods

“…Abs were produced in rabbits as described by Wang et al [29]. Female New Zealand white rabbits were immunized by intradermal and intramuscular injections of CAP haptens conjugated to KLH.…”

Application of computer-assisted molecular modeling for immunoassay of low molecular weight food contaminants: A review

“…Many immunoassays used for detection of low molecular weight food contaminants such as an algaecide [30], antibiotics [6,16,[31][32][33][34][35], cork taint [36], herbicides [37][38][39][40], mycotoxins [41,42], pesticides [43][44][45][46][47][48], veterinary drugs [49][50][51] and other chemicals [52][53][54][55][56] have been developed with the use of CAMM methods (Table 1). CAMM can be used to assist in hapten design, study antibody-antigen recognition in cross-reactivity studies and model antibody binding sites (Table 1).…”