Saratov Institute of Radiation, Chemical and Biological Warfare Defense, 410037 Saratov, Russia.
Talanta. 2003 Oct 17;61(2):195-202. doi: 10.1016/S0039-9140(03)00268-6.
Speciation of rhodium(III) in different acidic media has been studied by capillary zone electrophoresis (CZE). Depending on the nature of the acid, rhodium was shown to occur in the form of positive, neutral and/or negatively charged complexes. The relationship between the distribution of rhodium forms and its catalytic action on the oxidation of N-methyldiphenylamine-4-sulfonic acid by periodate ions has been investigated. It was found that only positively charged complexes of rhodium, such as those dominating in perchloric acid solutions, catalyzed a given reaction to form a colored oxidation product. The rate of the catalyzed reaction was optimized with respect to the pH, reagent and oxidant concentration levels, ionic strength, concentration of the catalyst, as well as the presence of interfering ions. The developed kinetic spectrophotometric method features rather high sensitivity (limit of determination 10 mug l(-1)) and tolerance for most platinum metals and was applied to a complex industrial sample of a platinum concentrate.
铑（III）在不同酸性介质中的形态已通过毛细管区带电泳（CZE）进行了研究。根据酸的性质，铑以正、中性和/或带负电荷的配合物形式存在。考察了铑形态的分布与其对高碘酸盐离子氧化 N-甲基二苯胺-4-磺酸的催化作用之间的关系。结果表明，只有带正电荷的铑配合物，如在高氯酸溶液中占主导地位的配合物，才能催化给定反应生成有色氧化产物。对反应的催化速率进行了优化，考察了 pH 值、试剂和氧化剂浓度、离子强度、催化剂浓度以及干扰离子的存在对其的影响。所建立的动力学分光光度法具有较高的灵敏度（检出限为 10μg·L（-1））和对大多数铂族金属的耐受性，并应用于铂精矿的复杂工业样品中。
