Application of a monoclonal antibody-based ELISA to the determination of carbaryl in apple and grape juices

Based on a high affinity monoclonal antibody, an enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of carbaryl (1-naphthyl N-methylcarbamate). For standards, the detection limit of the ELISA was 0.065 ng ml−1, with a I50 value of 0.706 ng ml−1. The ELISA was applied to the determination of carbaryl in apple and grape juices. The study of the influence of these matrices on the reliability of the assay indicated that the ELISA could determine carbaryl in fruit juices at the low ng ml−1 level simply by diluting the sample, without any cleanup or concentration step. Recovery and precision of the method were evaluated by spiking apple and grape juices with carbaryl in the 5–50 ng ml−1 range. No false negative or positive results were obtained. Coefficients of variation were lower than 13.0% in all cases, and mean recoveries were 100.0 and 92.2% for apple and grape juices, respectively. In addition of being precise and accurate, the method has proved to be simple and sensitive, with a quantification limit well below the maximum residue limits for carbaryl in apple and grape.