二安替比林对二甲氨基苯基甲烷-高碘酸钾催化光度法测定痕量铑

Catalytic Spectrophotometric Determination of Trace Rhodium with Diantipyryl-(p-dimethylamino)-phenylmethane-KIO_4 System

在磷酸介质和加热条件下，痕量铑（Ⅲ）能灵敏地催化高碘酸钾氧化二安替比林对二甲氨基苯基 甲烷（ＤＡＭＡＭ）的显色反应。研究了该催化反应的最佳实验条件及动力学参数，建立了一种动力学光度 法测定痕量铑的新方法。方法的线性范围为０～８４μｇ／Ｌ；检出限为６．２０×１０－７ｇ／Ｌ。催化反应的表观活 化能为８９．０３ｋＪ／ｍｏｌ，表观速率常数为２．５１×１０－４／ｓ，反应终止后至少稳定６ｈ。本法已用于某些催化剂中 铑的测定，其相对标准偏差为２．７％～３．２％；标准加入回收率为９８．２％～１０３．２％。

A kinetic method for the determination of trace rhodium based on the catalytic effect of Rh on the oxidative color reaction of diantipyryl-(p-dimethylamino) -phenylmethane (DAMAM) with potassium periodate in the H3PO4 medium and hot water bath was established. The optimum comdition and kinetic parameters of this reactionhis were studied in detail. The linear range of the determination was 0 ~ 80 μg/L, and the detection limit was 6.20× 10~7 g/L. The apparent activation energy of catalytic reaction was found to be 89.03kJ/mol,rate constant was 2.51 ×10-4/s. The system was stable at least at least 6h. The method has been applied to determine trace rhodium in some catalyst samples with the relative standard deviation of 2.7% ~ 3.2% (n=6) and recovery of 98.2% ~ 103.2% (n=5).