A sensitive chemiluminescent immunoassay to detect Chromotrope FB (Chr FB) in foods

Chromotrope FB (Chr FB) is a synthetic azo dye permitted for use in foods and medicines. An acceptable daily intake (ADI) of Chr FB was 0-0.5mg/kg in China. In this study, we synthesized a Chr FB hapten with an amino group to prepare its artificial immunogen. Polyclonal antibodies obtained from New Zealand rabbits were applied to develop an indirect competitive chemiluminescent immunoassay (icCLIA) to detect Chr FB in foods. A horseradish peroxidase (HRP)-luminol-H₂O₂ system was used to yield CL signal with p-iodophenol as an enhancement reagent. The method showed good specificity towards Chr FB and could detect as low as 0.02ngmL^-1 Chr FB in buffer, 0.07ngg^-1 in yoghurt candy, 0.07ngg^-1 in vitamin drink and 0.13ngg^-1 in bread. Compared with HPLC method, the proposed method is more sensitive by two orders of magnitude. The accuracy and precision of this method are acceptable and comparable with HPLC method. Therefore, the proposed method could be used for rapid screening of Chr FB in the mentioned foodstuffs.