Determination of Organophosphorus Pesticides in Vegetables and Fruit by an Indirect Competitive Enzyme-Linked Immunosorbent Assay (ic-ELISA) and a Lateral-Flow Immunochromatographic (LFIC) Strip Assay

Residues of pesticides in agricultural by-products may cause harm to human health. An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a competitive form of lateral-flow immunochromatographic (LFIC) strip were developed for the determination of methyl parathion and triazophos in agricultural by-products. In the optimized system for ic-ELISA, the limits of detection (LODs) for methyl parathion and triazophos were 1.39 and 1.94 ng/mL. The linear ranges for methyl parathion and triazophos were from 7.90 to 200 ng/mL and 4.47 to 170.19 ng/mL. The recoveries from agricultural by-products ranged from 84.16 to 106.96% and the coefficients of variation were from 0.77 to 6.45%. In the optimized LFIC system, good linearity was obtained for methyl parathion and triazophos between 5 and 200 ng/mL. The LODs of the CG-LFIC strip for methyl parathion and triazophos were 2.17 and 4.21 ng/mL. The coefficients of variation of the test strip were from 0.73 to 8.34%. Pears, apples, cucumbers, and lettuces spiked with methyl parathion and triazophos were employed to characterize matrix effects using the LFIC strip. The ic-ELISA and LFIC strip were simple and practical for the rapid determination of organophosphorus pesticides in agricultural by-products. Furthermore, the LFIC strip was suitable for on-site testing and rapid screening.