Dual-wavelength Dual-indicator Catalytic Spectrophotometry for Determination of Trace Copper in Water

A new dual-wavelength dual-indicator catalytic kinetic spectrophotometric method for the determination of trace copper(Ⅱ) was studied.The method was based on the copper(Ⅱ) catalyzing oxidation of acridine yellow and fuchsin acid by hydrogen peroxide in the Na_2HPO_4-NaH_2PO_4 at pH 5.5.The absorbance of the catalytic and uncatalytic systems were measured at 450 nm and 540 nm respectively.Under the optimum conditions,the linear range of determination was 0.60-32 μg/L and the detection limit was 0.24 μg/L.The method was very simple with high sensitivity and good selectivity.The method has been used to the determination of trace copper(Ⅱ) in water with satisfactory results.