Monoclonal antibody-based icELISA for sensitive monitoring fenpyroximate residue by hydrolysis conversion

Fenpyroximate is a systemic phenoxy pyrazole acaricide applied worldwide to prevent and control various phytophagous mites and has high activity against young mites, with residues increasingly being found in ecological environment and agricultural products. To identify its residues, four haptens of fenpyroximate were designed and an indirect competitive enzyme-linked immunosorbent assay (icELISA) based on monoclonal antibodies (2G4C7) was developed. Because the icELISA had higher sensitivity to the hydrolysate (Hapten A) of fenpyroximate, a method for indirectly determining the concentration of fenpyroximate was established by measuring the content of Hapten A. The assay had a working range of 0.07-1.49 ng/mL and a half-maximal inhibitory concentration (IC₅₀) of 0.34 ng/mL. It showed average recoveries of 77.0%-105.4 %, 72.3%-106.4 % in citrus and apple samples, respectively. The icELISA and UPLC-MS/MS test results for samples of various citrus cultivars are remarkably consistent. These results and data represent the icELISA is suitable and applicable for detecting fenpyroximate residuals in fruit and vegetable samples.