A colloidal gold immunochromatographic assay for on-site lead detection in vegetable oil

Lead (Pb) contamination in vegetable oil poses a significant threat to human health, and traditional detection methods have many limitations. In this study, a monoclonal antibody (mAb) against Pb²⁺ was prepared, and a colloidal gold immunochromatographic assay (CGIA) strip was developed for the on-site detection of Pb²⁺ in vegetable oil. The antigens Pb²⁺-ITCBE-KLH and Pb²⁺-ITCBE-BSA were synthesized and characterized by UV spectrophotometry. The obtained mAb, of IgG2a heavy chain and Kappa light chain subtype, had a high affinity constant of 7.3 × 10⁸ L mol^-1 and high specificity. Through optimization of the pH of the colloidal gold-labeled anti-Pb²⁺ mAb, components in the resuspension solution, and the sample pretreatment conditions, the developed CGIA test strip showed a limit of detection (LOD) of 0.021 μg kg^-1 for vegetable oil samples. The recovery of CGIA for spiked samples was 95.78-98.52%, consistent with that of inductively-coupled plasma mass spectrometry (ICP-MS), indicating its reliability. This CGIA strip provided a rapid and reliable method for detecting Pb²⁺ in vegetable oil, with potential for practical applications in ensuring vegetable oil quality and safety.