Kinetic Spectrophotometric Determination of Copper by Flow Injection Analysis in Cationic Micellar Medium

Abstract A sensitive catalytic kinetic method for the determination of nanogram amounts of copper by flow injection analysis (FIA) is described. The method is based on the catalytic effect of Cu(II) on the reduction of azure B by sulfide in the presence of cetyltrimethylammonium bromide (CTAB). The reaction is monitored spectrophotometrically at 647 nm. The linearity range of the calibration graph is dependent on the concentration of sulfide. The variables affecting the rate of the reaction were investigated and the optimal conditions were established. The method is simple, rapid, precise, sensitive, and widely applicable. The limit of detection is 9.2 ng mL−1, the calibration range is 50–1600 ng mL−1 of Cu(II), sampling rate is more than 60 determinations/hr, and the relative standard deviation of seven determinations of 400 ng mL−1 Cu(II) was 0.9%. The method was applied to the determination of copper in water samples.