Flow injection-chemiluminescent assay for the determination of superoxide dismutase activity

Superoxide dismutase (SOD) activity was measured using a flow injection-che miluminescent assay (FI-CLA) based on xanthine-xanthine oxidase dependent s uperoxide (O-2(.-)) formation. The mobile phase consists of 50 mM potassium phosphate buffer (pH 7.4) containing lucigenin (5 muM) and xanthine (0.3 m M). Under optimum conditions, bovine albumin did not affect chemiluminescen ce at concentrations of 1-1000 mug mL(-1) and KCN inhibited 100% of the Cu, Zn-SOD activity using 5 muL of a 0.23 mM concentration. The analysis of on e sample was done in less than 30 s with a relative standard deviation of /-3.1%. SOD activity in the biological samples was correlated to the amount of exogenously applied SOD. The FI-CLA method reported here appears to be one of the faster and more useful tools used to assay SOD activity.