Catalytic spectrophotometric determination of trace chromium(VI) based on the oxidation of hydrogen peroxide on ethyl violet

A new catalytic spectrophotometric method for the determination of trace chromium(Ⅵ) is developed,based on the catalytic effect of chromium(Ⅵ) on the oxidation reaction between hydrogen peroxide and ethyl violet in the medium of sulfuric acid.The linear range is 0.050.60 mg/L for chromium(Ⅵ) and the detection limit is 1.02×10-4 mg/L.The RSD of the method is 1.11% for determination of 2 μg Cr(Ⅵ)(n=10).In the presence of sodium fluoride and thiourea,most of common ions don't interfere in the determination of chromium(Ⅵ).The proposed method has been used for the determination of trace chromium(Ⅵ) in waste water and steel samples with satisfactory results.