Comparative analysis of three immunochromatographic test strips for rapid detection of cadmium ion in Asparagus

Summary Currently, there is increasing concern regarding the presence of cadmium ion (Cd 2+ ) residues in Asparagus, necessitating the development of a rapid, sensitive and effective detection method. Immunochromatographic detection techniques offer a swift and efficient primary screening approach, significantly reducing labour and material resources compared to traditional detection methods. In this study, we aimed to construct and optimise an immunochromatographic test strip method for precise determination of Cd 2+ content in Asparagus. To achieve this, monoclonal cadmium antibody (4A9) was prepared and conjugated with colloidal gold nanoparticles (AuNPs), latex microspheres (LM) and polydopamine (PDA) to create immunoprobes for test strip construction. We optimised key factors, such as probe parameters, strip assembly conditions and sample pretreatment methods. The sensitivity and detection capabilities of the three test strips were evaluated using actual Asparagus samples. The results demonstrated that all three immunochromatographic test strips exhibited high sensitivity, efficiency and rapidity in detecting Cd 2+ levels in Asparagus. Notably, the LM‐based and PDA‐based test strips showed outstanding performance, with a visual limit of detection (vLOD) of 0.1 ng mL −1 and an elimination value of 2.0 ng mL −1 . These findings underscore the promising potential of these test strips for practical cadmium detection in Asparagus samples.