Spectrophotometric determination of hydrogen peroxide and glucose based on hemin peroxidase-like catalyzed oxidation of bromopyrogallol red

In an ammonium buffer medium at pH 8.9-9.5, hemin exhibits mimetic peroxidase activity, and has a catalytic effect on the oxidative decoloration of bromopyrogallol red (BPR) with hydrogen peroxide. On this basis and in presence of ethanol as an effect-enhancing agent, a spectrophotometric determination of hydrogen peroxide is described with an apparent molar absorptivity of 4.00 x 10(4) mol(-1) cm(-1) and a linear range from 3.2 x 10(-7) to 3.2 x 10(-5) moll(-1) BPR has advantages over some of widely used chromogenic substrates in aspects of sensitivity, simplicity and detection wavelength, while hemin has better stability than peroxidase. The system can be easily coupled with a glucose oxidase-catalyzed reaction, and glucose in the concentration range of 6.0 x 10(-7) 3.2 x 10(-5) moll(-1) is spectrophotometrically determined. The method has been applied to the analyses of synthetic water and human serum samples. The Michaelis parameters and the mechanism of the mimetic peroxidase reaction are also investigated.