Quantitative Analysis of the Neonicotinoid Insecticides Imidacloprid and Thiamethoxam in Fruit Juices by Enzyme-Linked Immunosorbent Assays

Rapid and sensitive ELISAs have been applied to analyze imidacloprid and thiamethoxam residues in apple, grape, orange, and peach juices after simple dilution of the samples without any extraction and cleanup. The matrix interference of the fruit juices was eliminated after 100-fold dilution, and the ELISAs gave method LODs of imidacloprid and thiamethoxam in fruit juices down to 20 and 5 ng/g, respectively. Average recoveries of imidacloprid and thiamethoxam from the spiked fruit juices were in the range of 92-115% and 87-118%, respectively. The CVs of the recoveries ranged from 3 to 19% and from 6 to 19% for imidacloprid and thiamethoxam, respectively. The ELISA results were comparable to those obtained by a reference HPLC/MS method using pesticide-spiked samples, with reasonable correlation coefficients between 0.89 and 0.93 and regression coefficients (slopes) between 0.75 and 0.94.