2－（2－噻唑偶氮）－5－〔N，N－二羧基甲基）氨基〕苯甲酸与钯显色反应的研究及其应用

Study on the Color Reaction of 2-(2-Thiazolylazo)-5-[N,-N-dicarboxymethyl)amino]Benzoic Acid with Palladium and Its Application

报道了一种对钯离子具有高灵敏度和选择性的新试剂２－（２－噻唑偶氮）－５－［（Ｎ，Ｎ－二羧基甲基）氨基］苯甲酸（ＴＡＤＣＡＢ）。在０．５ｍｏｌ／ＬＨＮＯ＿３介质中，ＴＡＤＣＡＢ与Ｐｄ（Ⅱ）形成蓝色配合物，组成为Ｐｄ：ＴＡＤＣＡＢ＝１：２，最大吸收波长６５２ｎｍ。钯浓度在０～１．４μｇ／ｍＬ范围内符合比耳定律。用双波长法测定，表观摩尔吸光系数ε＿（６５２．０～５３３．６）＝８．２×１０￣４Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１），可以允许大量金属离子共存。所确立的方法无需掩蔽剂和其它分离手段，即可直接用于Ｐｔ－Ｐｄ催化剂中微量钯的测定，结果满意。

A new reagent 2-(2-thiazolylazo)-5-[(N,N-dicarboxymethyl)amino]benzoic acid(TADCAB)has been reported as a highly sensitive and selective chromogenic reagent for the determination of palladium.In a 0.5 mol·L￣(-1) nitric acid medium, palladium(Ⅱ)reacts with TADCAB to form a stable 1:2 blue chelate,It has a maximum absorption wavelength at 652.0nm.Beer' s law is obeyed Over a range of 0～1.4 μg Pd/mL.The apparent molar absorption coefficient is 8.2×104 L·mol-1·cm￣(-1)as determined by dual-wavelength spectrophotometry. Large amounts of coexisting elements can be tolerated.The proposed method has been applied satisfactorily to the direct determination of palladium in Pt-Pd catalysts.