Determination of N-Methylcarbamate Insecticide Metolcarb by Enzyme-Linked Immunosorbent Assay
Abstract The hapten of the N -methylcarbamate insecticide metolcarb, 3-{[1-(3-(methyl)phenyloxy)carbonyl]amino}propanoic acid (HOM), was synthesized and conjugated with the carrier proteins bovine serum albumin (BSA) and ovalbumin (OVA), respectively, by the active ester method. The conjugate of HOM-BSA was used as immunogen, and we prepared rabbits' anti-metolcarb serum, the titres of which were determined by noncompetitive indirect ELISA procedures and reached 1.28×10 6 . The results of the cross reaction indicate that the antiserum produced could specially recognize the insecticide metolcarb. After optimization of the ELISA conditions, such as ionic strengths, organic solvents, pH values, blocking agents, and so on, the proper parameters of ELISA procedure were determined, and an assay protolcol for the N -methylcarbamate insecticide metolcarb was established. On the basis of statistical analysis, the linear range of determination was from 1 to 104 ng/mL, IC50 was 40.74 ng/mL, limit detection was 0.08–0.10 ng/mL, intra-assay coefficient of variation (CV) reached 2.9%, and inter-assay CV reached 4.6%. The recoveries obtained by standard metolcarb addition to different samples such as rice, water, and soil were 80, 93.4, and 107%, respectively. This is the first time that polyclonal antibodies to the N -methylcarbamate insecticide metolcarb are produced, and the ELISA, used here for efficient and available detection of metolcarb, may become a convenient and satisfied analytical tool for monitoring metolcarb residues in environmental and agricultural samples.