Colloidal gold-based lateral flow immunoassay for detecting cyclosulfamuron residues in cereal samples

Cyclosulfamuron (CS) is a widely used sulfonylurea herbicide in plant cultivation and food production, and poses significant threats to ecological balance and food safety. To address this concern, we designed a novel CS hapten using computer-simulated semi-antigens. A monoclonal antibody (mAb) exhibiting high specificity and affinity was generated, with an affinity constant of 1.049×10 9 L/mol and a semi-inhibitory concentration (IC 50 ) of 4.94 ng/mL. Leveraging this anti-CS mAb, we constructed a rapid, visually detectable, quantitative lateral flow immunoassay (LFIA) to detect CS in cereals. Under the optimal conditions, the cut-off values were determined to be 100 μg/kg for brown rice and corn samples and 50 μg/kg for rice samples. The corresponding limits of detection values (LODs) were found to be 1.93 μg/kg in brown rice, 2.18 μg/kg in corn and 1.93 μg/kg in rice, respectively. The recovery rates ranged from 96.2% to 104.8% with coefficients of variation ranging from 3.5% to 6.4%, showing good agreement with the results obtained by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The proposed assay demonstrated robust analytical performance, with significant application potential for rapid, on-site detection.