2－（5－溴－2－噻唑偶氮）－5－二甲氨基苯甲酸测定微量钴（Ⅲ）的研究

Study of Color Reaction between Cobalt(Ⅲ)and 2-(5-Bromo-2-Thiazolylazo)-5-Dimethylaminobenzoic Acid

本文研究了２－（５－溴－２－噻唑偶氮）－５－二甲氨基苯甲酸（简称５－Ｂｒ－ＴＡＭＢ）与钴（Ⅲ）显色的最佳条件．实验结果表明．在乙醇介质中．ｐＨ＝３．７～５．４范围内，５－Ｂｒ－ＴＡＭＢ与钴（Ⅲ）形成稳定的蓝色络合物，络合比为Ｃｏ（３＋）：５－Ｂｒ－ＴＡＭＢ＝１∶２，表观摩尔吸光系数ε（６８４）＝１．０９×１０５Ｌ·ｍｏｌ（－１）·ｃｍ（－１），钴浓度在０～１５μｇ／２５ｍｌ范围内符合比耳定律．方法灵敏度高，选择性好，用于ＶＢ（１２）、含钴分子筛中钴含量的测定，结果满意．

The color reaction between Co(Ⅲ) and 2-(5-Bromo-2-thiazolylazo) -5-dimethylaminobenzoic acid(5-Br-TAMB) has been studied. The experimental results show that in the presence of ethanol at pH 3.7～5.4,Co (Ⅲ)reacts with 5-Br-TAMB to form a stable blue 1:2 complex with apparent molar absorptivity of 1.09×105L·mol cm at 684 nm. Beer's law is obeyed in the range of 0～15μg/25ml for CO(Ⅲ). The method has