Development of polyclonal ELISA for the N-methylcarbamate insecticide bendiocarb

A polyclonal antibody-based enzyme-linked immunosorbent assay (ELISA) method was developed for the N-methylcarbamate insecticide bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-yl methylcarbamate). Two novel haptens having dimethylbenzodioxyl and dimethylbenzofuranyl groups connected to oxyacetyl-γ-aminobutanoic acid and oxyacetyl-β-alanine spacer arm respectively were synthesised. The first hapten was conjugated to carrier proteins to make antigens that were used to raise polyclonal antibodies in rabbits. The antibodies specifically recognised bendiocarb and its metabolite 2,2-dimethyl-1,3-benzodiox-4-ol with an IC₅₀ value of 9 ppb (ng ml^-1). The assay was standardised using the competitive ELISA format at 0.0625 µg antibody concentration and at 1/10k pesticide-HRP dilution. Matrix effect studies were carried out in four vegetable and cereal food samples. Matrix effect elimination in cabbage, cauliflower and rice was achieved by simple dilution of the extract. Five different approaches were attempted to achieve matrix clean up in paddy rice. C-18 column and gel permeation column chromatography (GPC) helped in the matrix removal. The spike and recovery studies for all the four food samples gave a recovery in the range of 75-95%, thus indicating the efficiency of the matrix elimination procedures developed.