Spectrofluorimetric quantification of bilirubin using yttrium–norfloxacin complex as a fluorescence probe in serum samples

A simple and sensitive spectrofluorimetric method was developed to determine trace amounts of bilirubin (BR) using yttrium (Y3+)–norfloxacin (NFLX) complex as a fluorescence (FL) probe. NFLX can form a stable binary complex with Y3+ and markedly enhances the weak FL signal of the NFLX. The FL intensity of the Y3+–NFLX complex decreased significantly in the presence of BR in a buffer solution at pH=7.2. Under optimal conditions, the FL intensity decreased according to the BR concentration and showed a good linear relationship in the range of 0.03–2.3 μg mL−1 of BR with a correlation coefficient of 0.9988. The limit of detection for the determination of BR was 2.8 ng mL−1 with a relative standard deviation (RSD) of 1.55% for five replicate determination of 0.05 μg mL-1 BR. The presented method offers higher sensitivity with simple instrumentation and was applied successfully in detecting BR at low concentrations.