Production of the polyclonal antibody against Sudan 3 and Immunoassay of Sudan dyes in food samples.

In this study, 4-aminophenylacetic acid was covalently coupled to aniline to synthesize an intermediate hapten and the intermediate hapten was coupled to β-naphthol to synthesize a tentative hapten of Sudan 3. The hapten was coupled to bovine serum albumin as the immunogen to produce the polyclonal antibody. The obtained antibody was highly specific to Sudan 3, Sudan 1, and Para red, but showed relative low binding ability to Sudan 2, Sudan 4, and Sudan red G. After evaluation of different coating antigens, a heterologous indirect competitive immunoassay was developed to multidetermine the six red dyes in food samples. The cross reactivities to the six analytes were in a range of 21-105%, and the limits of detection were in a range of 0.1-0.8 ng/mL depending on the compound. Intra- and interassay recoveries from the standard fortified blank samples were in a range of 74.5-96.3% with coefficients of variation lower than 15.1%.