2-(2-噻吩偶氮)-5-二乙氨基酚与铬(Ⅲ)的显色反应及其应用

Colour Reaction of Chromium(Ⅲ) with 2- (2-Thienylazo)-5-diethylaminophenol and Its Application

在Ｐｈ ２．７—３．４的乙酸－乙酸钠缓冲溶液中，在沸水浴中加热２０ｍｉｎ，铬（Ⅲ）与２－（２－噻吩偶氮）－５－二乙氨基酚（ＴＡＤＡＰ）生成稳定的１：２ 螯合物，最大吸收波长λｍａｘ＝５６５ｎｍ，摩尔吸光系数。ε＝６．２４ｘ１０~４，铬（Ⅲ）浓度在０～１２μｇ／２５ｍＬ范围内遵守比尔定律，铬（Ⅲ）螯合物吸光度值至少可稳定４８ｈ．研究了干扰离子的影响及消除方法．本法具有较高的灵敏度和较好的选择性．用于电镀废水中铬的测定，获得了满意的结果．

In acetic acid-sodium acetate (pH2.7--3.4) buffer solution, heated in boiling water for 20min, chromium(Ⅲ)reacts with 2 - (2 - thienylazo) - 5 - diethylaminophenol (TADAP) to form the l: 2 chelate. The maximum absorbance is at 565nm and its molar absorptivity is 6.24x 10~4 L·mol^1·cm^-l. The concentration range of chromium(Ⅲ) odeying Beer's law is 0- 12ug/25mL. The chelate can remain stable at least 48 hours The effect of foreign ions and their elimination are also studied. This method has a good selectivity as well as a high Sensitivity. When it is used for the determination of chromium in waste water samples, satisfactory results are obtained.