Chemiluminescence Studies of the Oxidation of Ascorbic Acid with Copper(II) Catalyzed by Halide Anions and Its Application to the Determination of Halide Anions and Ascorbic Acid

Abstract

The oxidation reaction of ascorbic acid by copper(II) has been studied by chemiluminescence system of luminol/copper(II) in alkaline solution. Oxygen and halide anions (Cl, Br– and I–) can greatly catalyze the oxidation of ascorbic acid, which produces active oxygen (H2O2 and oxygen free radical) and sensitizes the CL emission of luminol. Based on the catalytic effects of halide anions, a direct CL method without conversion of these halide anions prior to the CL reaction for the determination of halide anions is first proposed. CL intensity is linear to the concentration of Cl–, Br– and I– in the range of 1.0 × 10–5–3.2 × 10–3 mol l–1, 1.0 × 10–5–3.2 × 10–3 mol l–1 and 4.6 × 10–5–4.2 × 10–3 mol l–1 respectively. Furthermore, in the presence of catalyst (oxygen and chloride anion), a sensitive and selective CL method for the determination of ascorbic acid is also proposed, the linear range and detection limit are 1.0 × 10–7–1.0 × 10–5 mol l–1 and 5.8 × 10–8 mol l–1, respectively.