新显色剂2-[2-噻唑偶氮]-5-二乙氨基苯甲酸与铑显色反应的研究

Color Reaction of Rhodium With a New Reagent 2-(2-Thiazolylazo)-5-diethylaminobenzoic Acid

本文合成了新显色剂2-[2-噻唑偶氮]-5-二乙氨基苯甲酸(TAEB),研究了它与铑的显色反应。结果发现,在pH4.0～6.5的缓冲溶液中,铑(Ⅱ)与TAEB形成一种绿色络合物。其最大吸收波长为674nm,表现摩尔吸光系数为1.44×10~5L·mol^(-1)cm^(-1)。铑含量在0～20μg/25ml范围内服从比尔定律。络合物中铑(Ⅱ)与TAEB的摩尔比为1:1。该方法灵敏度高、选择性好。常见的阴、阳离子不干扰,镍(Ⅰ)、钴(Ⅰ)和铜(Ⅰ)的干扰可用EDTA来消除,用于催化剂中微量铑的测定。结果令人满意。

A new chromogenic reagent 2-(2-thiazolylazo)-5-diethylaminobenzoic acid(TAEB) has been synthesized and its color reaction with rhodium was studied, In the buffer medium at pH 4.0～6.5, rhodium reacts with TAEB to form a stable complex, exhibiting an absorption maximum at 674nm, The apparent molar absorptivity was found to be 1.44 ×10~5L.mol(-1)cm^(-1). Beer's law was obeyed in the range of 0～20μg/25ml, The molar ratio of rhodium (Ⅲ): TAEB in the complex was estimated to be 1:1. The method is highly sensitive and selective. Common anions and cations do not interfere. The interferences of nickel(Ⅱ), cobalt(Ⅱ) and copper(Ⅱ) can be masked by EDTA, It was applied to the determination of trace amount of rhodium in catalysts with satisfactory results.