Development of ic-ELISA and colloidal cold-based immunochromatographic assay for red 2G detection in fruit drinks, red wine, and yoghurts

Red 2G (R2G), a cheap industrial colorant, cannot be added to food. An anti-R2G monoclonal antibody (mAb) was prepared by immunizing mice with the conjugate of R2G hapten and protein, which based on the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) method. Indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and colloidal gold-based immunochromatographic assay (CG-ICA) methods were used to determine R2G in fruit drinks, red wine, and yoghurts. A standard curve of the developed ic-ELISA showed that the IC50of the anti-R2G mAb was 1.02 ng/mL, and limit of detection value (LOD) was 0.21 ng/mL. For the CG-ICA developed, the visual limit of detection values (vLOD) were 2 ng/mL and cut-off values of 100 ng/mL in samples. The results indicated that these two methods could be used to quickly detect R2G in fruit drinks, red wine, and yoghurts.