铱催化高碘酸钾氧化钍试剂动力学光度法测定痕量铱

<title>Kinetic spectrophotometric determination of trace iridium with oxidation of thoron by KIO_4

在磷酸和热水浴中,铱(Ⅳ)对高碘酸钾氧化钍试剂的反应具有催化作用,依此建立了测定铱的新催化光度法。铱的浓度在0.20μg/10mL～2.0μg/10mL范围内与催化反应速率有良好的线性关系,检出限为6.24×10-3μg/mL。对0.50μg/10mLIr(Ⅳ)测定的相对标准偏差为2.0%(n=10)。该催化反应对铱(Ⅳ)和钍试剂分别为一级反应,其表观活化能为81.66kJ/mol。实验了40多种共存离子的影响,大多数的常见离子不干扰。用该方法测定岩矿和冶金产品中铱的含量,相对标准偏差为1.0%～1.1%,加标回收率为95%～100%。

<Abstrcat>A new catalytic spectrophotometric method for determination of iridium was established based on its catalytic effect on the oxidation fading of thoron by KIO4 in H3PO4 medium in the hotwater bath. A linear relationship was obtained between the reaction rate and the concentration of Ir(Ⅳ)in the range of 0.2 μg/10mL～2.0 μg/10mL with detection limit of 6.24×10-3 μg·mL-1. The relative standard deviation for the detection of 0.050 μg/mL of Ir(Ⅳ) was 2.0% (n=10). The catalytic reaction was firstorder for both Ir(Ⅳ) and thoron with the apparent activation energy of 81.66 kJ·mol-1. The studies on the effects of more than 40 foreign ions indicated that most common ions did not interfere. The method was applied to the determination of trace iridium in some ores and metallurgical products samples with RSD of 1.0～1.1 % and recovery of 95 %～100 %.