Spectrophotometric catalytic determination of trace amounts of selenium based on the reduction of azureA by sulphide

A sensitive catalytic kinetic spectrophotometric method for determining ng ml(-1) concentrations of selenium is described. The method, based on the catalytic effect of Se (IV) on the reduction of azureA by sulphide, is monitored spectrophotometrically at 600 nn. The linearity range of the calibration graph is dependent on the concentration of sulphide. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. The method is simple, rapid, precise, sensitive, free from many interferences and is widely applicable. The limit of detection is 2.5ng ml(-1) of Se. The relative standard deviation of seven determinations of 100 ng ml(-1) Se was 1.5 %. The method was applied to the determination of selenium in spiked water, Kjeldahl tablets, synthetic samples and health care products.