Inhibitory kinetic spectrophotometric determination of trace antimony in water samples based on oxidation of H_2O_2 on arsenazo I

On the basis of inhibiting effect of trace amounts of antimonyⅢ on the discoloring reaction of arsenazo I(ASA I) in the KH2PO4-NaOH medium,a new kinetic spectrophotometric method for the determination of antimonyⅢ has been developed.The factors such as acidity,reaction time and temperature,influence of coexisting ions were discussed.The optimum reaction conditions were established.The apparent rate constant and apparent activation energy of the reaction are found as 1.90×10-3/s and 79.21 kJ/mol respectively.The linear range is 4.0-48 μg/L and the detection limit is 2.53×10-7 g/L for antimony.This method has been used to detect trace amounts of antimony in water samples and the relative standard deviation(RSD) is lower than 2%,and the recovery is from 98.5% to 104.3%.