A monoclonal immunoassay for carbofuran and its application to the analysis of fruit juices

Monoclonal antibodies (MAbs) for the carbamate pesticide carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) were obtained by immunizing mice with the hapten 3-[[(2,3-dihydro-2,2-dimethyl-7-benzofuranyloxy) carbonyl]amino] propanoic acid (BFNP) conjugated to bovine serum albumin (BSA). Based on one of these MAbs in combination with an heterologous hapten, an indirect enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of carbofuran. For standards, the detection limit of the ELISA was 0.2 ng ml(-1), with a I-50 value of 1.8 ng ml(-1). Cross-reactivity studies showed that the immunoassay was quite specific for carbofuran since, of the six N-methylcarbamates assayed, only bendiocarb was significantly recognized (17.4%). The ELISA was applied to the determination of carbofuran in apple, grape, and pineapple juices. Recovery and precision of the method were evaluated by spiking juices with carbofuran at 25, 50, and 100 ng ml(-1). Coefficients of variation were below 15% in most cases, and mean recoveries were 112.6, 107.4, and 115.4% for apple, grape, and pineapple juices, respectively. Therefore, the developed ELISA was able to determine carbofuran at levels below the maximum residue limits simply by diluting the sample, without the need for cleanup or sample concentration.