高碘酸钾氧化鸡冠花红动力学光度法测定痕量铑

Kinetic spectrophotometric determination of trace rhodium with oxidation of amaranth by potassium periodate

在磷酸溶液和热水浴中，Rh（Ⅲ）对高碘酸钾氧化鸡冠花红的反应具有催化作用，依此建立了测定铑的新催化光度法。铑质量浓度在0-0.10μg/mL范围内与催化反应速率有良好的线性关系，检出限为7.0×10^-3μg/mL。对0.04μg/mL Rh（Ⅲ）测定的相对标准偏差为2.5%（n=10）。该催化反应的表现活化能为81.36kJ/mol。试验了20多种共存离子的影响，大多数常见离子不干扰。该方法用于测定铑铝基催化剂中铑的含量，相对标准偏差为1.4%-1.6%，加标回收率为96%-103%。

A new catalytic spectrophotometric method for the determination of trace rhodium was established based on its catalytic effect on the oxidation of the amaranth （4-sulfo-1-naphthylazo-2-naphthol-3,6-disulfonic trisodium） by KIO4 in H3PO4 medium and hot-water bath. A linear relationship was obtained between the reaction rate and the concentration of Rh（Ⅲ） in the range of 0-0. 10μg/mL. The detection limit was 7.0×10^-3μg/mL. The relative standard deviation for the detection of 0.04 μg/mL Rh（Ⅲ） is 2.5% （n= 10）. The apparent activation energy of the catalytic reaction is 81.36kJ/ mol. The effects of more than 20 kinds of foreign ions were tested and the interference from many common ions could be tolerated. The method has been applied to the determination of trace rhodium in the Rh-Al catalysts with the RSD of 1.4-1.6% and the recovery of 96-103%.