Chemiluminescence arising from the oxidation of bilirubin in aqueous media

Novel chemiluminogenic redox reactions of bilirubin in aqueous media are reported. N-bromosuccinimide and sodium hypochlorite were the oxidants which generated the most intense radiation and the corresponding reactions were monitored using a batch chemiluminometer. Consequently, the reaction of bilirubin with N-bromosuccinimide was further investigated using a flow injection analyser and the reaction, with hypochlorite, was further examined by using a continuous flow analyser in order to automate the procedure. The results indicate that both procedures are very sensitive (batch procedure with NaClO: linear range 0.2–20 μg ml−1; 3σ detection limit 50 ng ml−1) since bilirubin at concentrations less than 1 μg ml−1 can be easily and reproducibly measured. Albumin interferes seriously by enhancing the emission.