Broad-Specificity Immunoassays for Detecting Prochloraz and Its Metabolites in Grapes and Water

This study aimed to develop broad-specificity antibodies for detecting prochloraz and its metabolites. Initially, three haptens were designed and identified through computational chemical methods, and the hapten H2 was the optimal candidate. Using H2-BSA as an immunogen, the monoclonal antibody 9C3 was prepared to recognize PCH and two metabolites, BTS44595 and BTS44596. The broad-specificity recognition mechanism revealed that the “2,4,6-trichlorophenyl” moiety of the three targets is completely encapsulated in the binding pocket of mAb 9C3 and that hydrophobic forces play crucial roles in binding. Furthermore, an indirect enzyme-linked immunosorbent assay and a colloidal gold immunochromatographic assay for detecting prochloraz residues in grapes and river water samples were developed. The IC₅₀ of ic-ELISA was 8.08–15.07 ng/mL, with recovery rates ranging from 73.80% to101.13%. In addition, the visual detection limit of GICA was 250–500 ng/mL, with IC₅₀ values ranging from 98.04 to 126.29 ng/mL and CRs ranging from 67.2 to 78.02%. The accuracy and precision of both immunoassays were validated by LC–MS/MS.