Dual-wavelength dual-indicator catalytic spectrophotometric determination of trace copper

A new dual-wavelength and dual-indicator catalytic kinetic spectrophotometric method for the determination of trace amount of copper was studied.It was based on copper(Ⅱ) catalyzing oxidation of rhodamine B and methylene blue by hydrogen peroxide in a buffer medium of HAc-NaAc(pH 4.0).The absorbances of the catalytic and uncatalytic systems were measured at 540 nm and 660 nm.The linear range of determination was 0.00080～0.048 μg/mL.The detection limit was 4.0×10-11 g/mL.The method was applied to the determination of copper in water with satisfactory results.