Potential Application of Immunoassay for the Detection of Pesticide Residues in Agriculture

Abstract

In Taiwan, the Agricultural and Forestry Agency (AFA) and Food and Drug Administration (FDA) routinely monitor the pesticide residues in agricultural products; samples were collected from production districts, packing sites and all kinds of markets. Currently the multi-residue testing methods of pesticides promulgated by the Ministry of Health and Welfare can determine the residues of 373 pesticides or their metabolites. However, expenses for the installation of needed analytic instruments, labor, and other cost are too expensive for most people, besides it cannot prevent the risky shipments in time from further trade. A rapid bioassay of pesticide residues (RBPR) method targeting on the neurotoxic orgranophosphorus and carbamate insecticides was developed by Taiwan Agricultural Research Institute in 1985 using the acetylcholinesterases extracted from a susceptible housefly strain. In 2017, 360 RBPR stations inspected 1.26 million shipments and a total of 37 tons of agricultural products with toxicity risk were destroyed. Since many of these toxic insecticides were banned in the past two decades, research on developing immunoassay, aiming at 30 insecticides and fungicides that were frequently found in violated fruits and vegetables by FDA, was launched in 2011 to strengthen the RBPR stations with enhanced residue control capability. In a 4-year program, highly specific and sensitive antibodies against 18 pesticides as well as direct and indirect competitive ELISA protocols have been developed with the capability of reaching the detection limits ranging from 0.01 to 2.24 ppb. Commercial test strips and ELISA kits have been under development through technical transfer of the antibodies and the assay protocols to biotechnology companies since 2016. The first product is a test strip that can detect the residue of dimethomorph in 10 min with the cut-off value of 1 ppm. By making adequate dilutions during the extraction process, the rapid test is able to obtain the result that meets the tolerance standard of various crops, e.g., 0.6 ppm and 2.5 ppm for onion and small leafy vegetables, respectively.