在0.01 mol·L-1硫酸介质中,95 ℃水浴加热10 min时,痕量铱(Ⅲ)对过氧化氢氧化亮绿褪色反应有显著的催化作用。据此提出了催化动力学光度法测定痕量铱(Ⅲ)的方法。该催化反应对铱(Ⅲ)为一级反应,总反应为准一级反应。催化反应的表观速率常数为7.383×10-4s-1,表观活化能为65.27 kJ·mol-1。铱(Ⅲ)的质量浓度在0.06 mg·L-1以内与吸光度的减小(ΔA)呈线性关系,检出限(3s/k)为1.152×10-7g·L-1。方法用于分子筛和活性炭样品中铱(Ⅲ)量的测定,回收率在97%~104%之间。

In 0.01 mol·L-1 H2SO4 medium and heated in a water bath at 95 ℃ for 10 min, the oxidative color-fading reaction of brilliant green with H2O2 was remarkably catalyzed by the presence of trace amount of Ir(Ⅲ). Based on these facts, a catalytic kinetic photometric method for determination of trace amount of Ir(Ⅲ) was proposed. It was proved that the catalytic process was a first order reaction for Ir(Ⅲ) and a pseudo first order reaction for total reaction. Values of apparent rate constant and apparent activation energy were found to be 7.383×10-4s-1 and 65.27 kJ·mol-1 respectively. Linear relationship between the values of decrease in absorbance (ΔA) and mass concentration of Ir(Ⅲ) was obtained in the range within 0.06 mg·L-1. Detection limit (3s/k) of the reaction found was 1.152×10-7g·L-1. In analyzing samples of molecular sieve and activated carbon by this method for Ir(Ⅲ) contents, giving recovery in the range of 97%-104%.