2-(3,5-二氯-2-吡啶偶氮)-5-二甲氨基苯胺与钴显色反应的研究及其应用

Colour reaction of 2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminoaniline with cobalt and its application

研究了新显色剂2-(3,5-二氯-2-吡啶偶氮)-5-二甲氨基苯胺与钴(Ⅱ)的显色反应。在 pH3.5～9.0范围内,试剂与钴(Ⅱ)形成2:1的稳定配合物,吸收峰位于548nm。在0.6～3.8mol/L 盐酸溶液中,配合物的最大吸收峰位于612nm,摩尔吸光系数为1.16×10~5L·mol^(-1)·cm^(-1)。钴含量在0～0.6μg/mL 范围内符合比尔定律。方法用于矿样和钢样中钴的测定,结果满意。

A highly sensitive and selective method forthe spectrophotometric determination of Co hasbeen developed.In a pH 3.5～9.0 medium 2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminoani-line(3,5-diCl-PADMA)reacts with Co(Ⅱ)toform a red complex exhibiting an absorptionmaximum at 548 nm.In a medium of 0.6～3.8mol/L HCl the complex can be changed into ablue complex exhibiting an absorption maximumat 612 nm.The molar absorptivity is 1.16×10~5L·mol^(-1)·cm^(-1)at 612nm.Beer's law is obeyed inthe concentration range of 0～0.6 μg/mL of Co.The molar ratio of Co to 3,5-diCl-PADMA is1:2.The method is simple and rapid,and hasbeen used for the determination of Co in min-erals and steel with satisfactory results.