Dual-wavelength catalytic spectrophotometric determination of trace copper in copper-hydrogen peroxide-arserazo III-brilliant green system

A new dual-wavelength dual-indicator catalytic kinetic spectrophotometric method for the determination of trace copper (Ⅲ) was studied.The method was based on copper (Ⅲ) catalytic effect on oxidation of arserazo (Ⅲ) and brilliant green by hydrogen peroxide in the medium of HAc-NaAc(pH 3.0).The absorbance of catalytic and uncatalytic systems are measured at 530 nm and 620 nm.Under the optimum conditions,the linear range of determination of copper (Ⅲ) is 0.000 2-0.10 μg/mL.The detection limit is 4.3×10-10g/mL.The relative standard deviation is 2.8% for 0.040 μg/mL copper(n=10).The method has been used to the determination of trace copper(Ⅲ) in water with satisfactory results.