2－［2′－（6′－甲氧基－苯并噻唑）偶氮］－5－二甲氨基苯甲酸光度法连续测定铁和镍

Continuous Spectrophotometric Determination of Iron and Nickel with 2-[2'-(6'-Methoxy-benzothiazolyl)azo]-5-dimethylaminobenzoic Acid

研究了新试剂２－［２′－（６′－甲氧基－苯并噻唑）偶氮］－５－二甲氨基苯甲酸（ＭＯＢＴＡＭＢ）与Ｆｅ（Ⅱ），Ｎｉ（Ⅱ）的显色反应。在混合表面活性剂（ＴｒｉｔｏｎＸ－１００－ＳＤＳ）存在下，于ｐＨ５．２的ＨＡｃ－ＮａＡｃ缓冲溶液中，Ｆｅ（Ⅱ），Ｎｉ（Ⅱ）与ＭＯＢＴＡＭＢ反应均形成１：２的稳定络合物。前者最大吸收波长为６５１ｎｍ，后者最大吸收波长为６５８ｎｍ。选定６５６ｎｍ为测定波长，测得表观摩尔吸光系数分别为ε＿Ｆｅ－ＭＯＢＴＡＭＢ＝８．３×１０￣４，ε＿Ｎｉ－ＭＯＢＴＡＭＢ＝１．２９×１０￣５。铁浓度在０～１１μｇ／２５ｍｌ、镍浓度在０～８μｇ／２５ｍｌ范围内符合比尔定律。利用ＮａＦ掩蔽Ｆｅ￣（３＋），可不经分离连续测定铁、镍。本方法反应灵敏度高、选择性好、操作简便，用于铝合金中铁、镍的连续测定，结果满意。

In the presence of mixed surfactants (TritonX-100-SDS),the colour reaction of 2-[2'-(6'-methoxy--benzothiazolyl)axo]-5-dimethylaminobenzoic acid (MOBTAMB) as a new reagent with Fe(Ⅱ) and Ni (Ⅱ) is studied.In a buffer solution of HAc-NaAc at pH5.2, both Fe(Ⅱ) and Ni(Ⅱ) react with MOBTAMB to form 1:2 stable complex. The maximum absorption of complexes are 615nm and 658nm respectively.The determination wave length is 656nm. The apparent molar absorptivity of complexes of iron and of nickel are 8.63×10￣4L·mol￣(-1)·cm￣(-1) and 1.29×10￣5L·mol￣(-1)·cm￣(-1)·respectively.Beer's law is obeyed for iron in the range of 0-11μg/25ml and for nickel in the range of 0-8μg/25ml Iron and nickel can be continuously determined without separation by using NaF to mask Fe(Ⅲ).The method is sensitive, selective and simple. It has been applied to the determination of Fe and Ni in aluminium alloy with satisfactory results.