Catalytically kinetic spectrophotometry for the determination of trace chromium(VI) and research of its reaction mechanism

A new catalytically kinetic spectrophotometry was studied for the determination of trace chromium(Ⅵ),based on the remarkably catalytic effect of chromium(Ⅵ)on the oxidation of Alizarin S by hydrogen peroxide with 1,10-phenanthroline(phen)as activating agent in HAc-NaAc buffer solution(pH 5.0).Under the conditions of λmax=422 nm and constant temperature(86 ℃),indicator reaction is followed spectrophotometrically by measuring the absorbance change with the method of fix time.Experimental conditions were optimized by orthogonal test and the kinetic parameters were also investigated.The detection limit of the method is 3.3 μg/mL,and the linear range is 0~200 μg/L.This method has been successfully applied for the determination of trace chromium(Ⅵ)in lake water and waste water.The mechanism of reaction was also discussed.