Trace Determination of Superoxide Dismutase by Anodic Scan Pulse Voltammetry

Abstract

This assay for superoxide dismutase (SOD) involves two electrode reactions: 1) the generation of a substrate (O₂^-) by a one-electron reduction of dissolved oxygen at a constant potential of -1.0V in a pH 11.0 borate-carbonate buffer solution containing 2×10^-4mol/l EDTA and 2.4×10^-4mol/l triphenylphosphine oxide, and 2) the detection of a residual substrate, which results from an SOD-catalyzed reaction at -0.1V by one-electron oxidation with anodic scan pulse voltammetry. By the use of a hanging mercury drop electrode (a static mercury drop electrode) and with a sequence-control technique, these reactions are so strictly controlled that an SOD as low as 10^-12mol/l can be determined within a short time (<30s) under automatic operation.