Organic solvent-free immunoassay for quantitative detection of neonicotinoid acetamiprid residues in agricultural products

A completely organic-solvent free analytical method for a neonicotinoid insecticide acetamiprid with water-based extraction and highly sensitive direct competitive enzyme-linked immunosorbent assay (ELISA) has been proposed. The analytical sensitivity (I50 value) and the limit of detection of the proposed ELISA were, respectively, 0.16 ng mL−1 and 0.015 ng mL−1. The ELISA showed no cross-reactivity to other structurally related neonicotinoid analogues excluding thiacloprid (43.8%). After crop samples were extracted with water, the aqueous sample extracts were adequately diluted with water before determination. No marked matrix interference was observed except for Chinese chive. However, problematic interference was found in the sample dissolved by homogenization with aqueous phosphoric acid. The average recoveries of acetamiprid were 89–118% with relative standard deviation of less than 10%. Acetamiprid-incurred fruiting vegetable samples were analyzed using the proposed method and a Japanese official method based on chromatographic techniques. Results obtained using the respective methods were statistically comparable.