A new detection method for the long residual herbicide fomesafen based on the anti-immune complex peptide

Fomesafen, a diphenyl ether herbicide widely used for broadleaf weed control in soybean fields. Herbicide causes persistent soil pollution, damaging microorganisms and threatening agricultural products safety, necessitating rapid detection methods. This study employed phage display to identify 14 anti-immune complex peptides (AIcPs) targeting Fomesafen. The optimal peptide, AIcP-F21, enabled a highly sensitive noncompetitive enzyme linked immunosorbent assay (ELISA) with an SC₅₀ of 0.45 ng/mL-3.5 times more sensitive than competitive ELISA. A phage-free AIcP-F21 was synthesized for noncompetitive lateral flow immunoassay (NLFIA) test strips, achieving a visual detection limit (vLOD) of 0.31 ng/mL. This represents an eight-fold sensitivity improvement over competitive methods. The assays demonstrated excellent specificity with no cross-reactivity to analogous compounds. Validation using spiked samples and real samples analysis yielded results consistent with UPLC-MS/MS, confirming reliability. The new noncompetitive immunoassay method developed in this study is of great significance for monitoring and evaluating the residues of fomesafen in the environment and agricultural products.