Abstract：Based on the obvious catalytic effect of trace nikel (Ⅱ) on the fading reaction of alizarin red S (ARS) oxidized by H2O2 in the buffer of NH3·H2O-NH4Cl at pH 9.00, a new sensitive kinetic spectrophotometric method for the determination of trace nickel was developed. The influence of acidity, concentration of reactants, surfactants, reaction temperature and reaction time were discussed, and the optimal determination conditions were established. The effect of lots of coexisting ions on reaction system were also investigated, which showed that most common ions had no interference on determination and the interference of Fe3+ and Cu2+ could be removed by adding NH3F solution and KI solution, respectively. The maximum absorbance peak of system was 520 nm. The linear range was 0.02-2.8 μg/mL. The detection limit was 0.008 μg/mL. The apparent activation energy was 71.68 kJ/mol. The method has been applied to the determination of trace nickel in alloy CRMs, and the results were in agreement with certified values.
