Catalytic spectrophotometric determination of trace chromium(VI)in water with chromium(VI)-potassium bromate-ethyl violet system

A new catalytic spectrophtometry of the determination trace chromium(Ⅵ)was introduced,based on the catalytic effect of chromium(Ⅵ)on the oxidation decoloration reaction of ethyl violet by potassium bromate in the medium of H3PO4.The determination conditions and interference of coexistence elements were studied.The linear range of determination was 0.004-0.094 μg/mL for Cr(Ⅵ).The detection limit was 1×10-9 g/mL.The method could be used to detect trace chromium(Ⅵ)in tap water,rivulet water and electroplating waste water,with the relative standard deviation of below 2.5% and the average recovery of 97%-102%.