A Sensitive, Rapid, On-Site Detection of Diflubenzuron in Food via a Colloidal Gold-Based Test Strip

Diflubenzuron (DFB), a benzoylurea insecticide widely used in fruits, vegetables, cereals, and edible fungi, is increasingly detected in food. It has been linked to endocrine disruption, hematological effects, developmental toxicity, DNA damage, and ecological risks in aquatic organisms. These concerns, together with strict maximum residue limits, highlight the need for rapid, field-deployable detection methods. Herein, we developed a quantitative colloidal gold lateral-flow immunoassay for rapid DFB detection within 10 min. The optimized assay achieved a limit of detection (LOD) of 0.02 ng mL^-1, a limit of quantification (LOQ) of 0.067 ng mL^-1, and a linear range of 0.07-100 ng mL^-1 (R² = 0.9998), with high selectivity. Validation in eight food matrices (milk, chicken, mushrooms, pear, Chinese cabbage, rice, dried chili, and peanut) showed recoveries of 97.6-110.0% with RSDs of 2.1-4.9%. Results were consistent with LC-MS analysis, demonstrating that this assay provides a sensitive, practical, and rapid tool for screening DFB residues.