Preparation of anti-Sudan red monoclonal antibody and development of an indirect competitive enzyme-linked immunosorbent assay for detection of Sudan red in chilli jam and chilli oil.

Sudan dyes are banned to be used in food additives because of the carcinogenicity of their metabolites. A rapid and sensitive indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect the residues of Sudan dyes. Novel immunogen and coating antigen were synthesized via glutaraldehyde linking. The hapten-bovine serum albumin (BSA) was applied as immunogen and the hapten-ovalbumin (OVA) was served as coating antigen. The monoclonal antibody obtained showed high sensitivity to Sudan I with an IC(50) value of 1.7 μg L(-1) in buffer and was suitable to detect the residues of Sudan red in food products. The specificity of the assay was studied by measuring cross-reactivity of the antibody with the structurally related compounds of Sudan II (<1%), Sudan IV (<1%) and para red (120%). Chilli jam and chilli oil samples spiked with Sudan dyes were analyzed by the method. The detection limit (LOD) of the ELISA method applied in chilli jam and chilli oil was 9.0 μg L(-1) and 19.6 μg L(-1), respectively. The recovery rates of Sudan-I in chilli oil and chilli jam were in the range of 80%-110% with coefficients of variation <25%. The intra-assay variation and inter-assay variation in buffer were both <9%.