Kinetic spectrophotometric determination of trace copper based on its catalytic effect on the oxidation of evans blue by hydrogen peroxide

Based on the catalytic effect of copper on the oxidation reaction of evans blue and H2O2 in the NaAc-HAc medium,a new kinetic spectrophotometric method for determination of trace copper(Ⅱ) was established.The optimum conditions and kinetic parameters were investigated.The apparent activation energy and rate constan were found to be 24.65kJ/mol,and 4.86×10-2s-1,respectively.Under the selected conditions,a good linear relationship could be obtained between the catalytic reaction rate and the concentration of copper(Ⅱ) in the range of 0.48～20 μg/L,with detection limit of 2.06×10-8g/L.The method has been successfully applied for the determination of copper in tap water and waste water with the relative standard deviation of 2.5% and 1.9%,and recovery of 99.6% and 99.4%,respectively.