Colloidal gold-based immunochromatographic assay for the detection of carmoisine in soft drinks

Carmoisine (CMS) is a synthetic azo colorant that can be used as a food colorant in products such as candy. However, due to potential health risks associated with carcinogenic, child development and allergic reactions , its use is strictly regulated. We have developed a colloidal gold immunochromatographic assay (CG-ICA) based on a highly sensitive monoclonal antibody (mAb) for the rapid and sensitive detection of CMS in food products. This study proposes a novel hapten and evaluates its structure through computer-aided analysis based on molecular structural similarity. Then, a mAb was successfully prepared, with a half-maximal inhibitory concentration of 0.20 ng/mL and a limit of detection (LOD) of 0.03 ng/mL. The CG-ICA strip demonstrated a LOD of 0.48–0.58 μg/L for three soft drink types, achieving recovery rates between 90.78% and 109.61% and a coefficient of variation (CV) between 2.39% and 5.24%. The accuracy of the method was further validated by liquid chromatography–tandem mass spectrometry (LC–MS). Without requiring complicated purification steps, the simple operation and rapid result-yielding ability of CG-ICA within 20 min demonstrate its suitability for field rapid screening of CMS in soft drinks. The method developed in this study represents a new exploration for CMS detection and provides a direction for the rapid screening of similar colorants. • A new hapten was designed to develop highly sensitive anti-CMS monoclonal antibody . • The performance of CMS hapten was validated by simulation and experimental results. • A rapid CG-ICA method detected CMS in soft drinks with vLOD of 2 μg/L.