Highly sensitive spectrofluorimetric determination of hydrogen peroxide with β-cyclodextrin–hemin as catalyst

Abstract

β-Cyclodextrin (CD)–hemin was studied as a replacement for horseradish peroxidase (HRP) in the spectrofluorimetric determination of H₂O₂. The optimum concentrations of substrate and β-CD–hemin were studied. pH 10.4 was found to be the optimum value for the experiment. The influence of different buffers on the peroxidase activity of β-CD–hemin was tested and it was found that the peroxidase activity of β-CD-hemin was enhanced by NH₃. The oxidation product 2,2′-dihydroxy-4,4′-dimethylbiphenyl was monitored fluorimetrically, with a detection limit of 3.4 × 10^–9 mol l^–1 of H₂O₂. A linear calibration graph was obtained over the H₂O₂ concentration range 3 × 10^–8–8 × 10^–6 mol l^–1, with a correlation coefficient of 0.9993. The relative standard deviation at an H₂O₂ concentration of 2 × 10^–6 mol l^–1 was 1.8%.