Enzyme immunoassay for the determination of carbaryl residues in agricultural products

Carbaryl is one of the most important N-methyl carbamate insecticides used all over the world. To determine carbaryl residues in agricultural products (apple, pear, Chinese cabbage, rice and barley), a competitive enzyme-linked immunosorbent assay (ELISA) method was employed, and a simple and efficient extraction method for the rapid detection of carbaryl in agricultural products was developed with recoveries greater than 90%. After liquid extraction, sample extracts diluted with buffer were analysed by ELISA directly. Matrix effects can be avoided when a 1:20 dilution of apple, pear, rice and barley samples and a 1:50 dilution of Chinese cabbage samples with 0.5% fish skin gelation in phosphate-buffered saline containing 5% methanol. Sample extracts were analysed by ELISA and HPLC, and results obtained by two methods correlated well; the correlation was greater than 0.9.