Catalytic spectrophotometric determination of trace chromiumVI-with chromiumVI-acidic chrome blue K-hydrogen peroxide system

A new catalytic spectrophotometric method for determination of trace chromium* has been developed.The method is based on the catalytic effect of chromium* on the oxidation of acidic chrome blue K by hydrogen peroxide in (CH_2)_6N_4-HCl buffer solution(pH 5.5).The apparent activation energy of catalytic reaction is 84.82 kJ/mol.The method has the feature of high sensitivity and selectivity and wide linear range.The linear range for the determination of chromium is 0-12 μg/25 mL and the detection limit is 1×10~(-3) μg/mL.Common foreign ions have no interfering effect on the determination of Cr* by adding an appropriate amount of EDTA.The method has been applied to the determination of trace chromium in the certified reference sample of iron with satisfactory results.