Spectrofluorimetric determination of bilirubin in serum samples

A new spectrofluorimetric method was developed for determination of trace amount of bilirubin. Using oxytetracycline-Eu(3+) as a fluorescent probe, in the buffer solution of pH = 7.3, bilirubin can reduce remarkably the fluorescence intensity of the oxytetracycline-Eu(3+) complex at λ = 612 nm and the reduced fluorescence intensity was in proportion to the concentration of bilirubin. Optimum conditions for the determination of bilirubin were also investigated. The linear range and limit of detection for the determination of bilirubin were 5.0 × 10(-7) , 3.0 × 10(-5) and 7.7 × 10(-8)  mol  L(-1) , respectively. This method is simple, practical and relatively free of interference from coexisting substances and can be successfully applied to assess bilirubin in serum samples and compared with the modified Jendrassik-Grof method in clinical analysis. The quenching mechanism of the fluorescence intensity in the system is also discussed.