2-(2-噻唑偶氮)-5-[(N,N-二羧基甲基)氨基]苯磺酸的分析特性及其与钯显色反应的研究

Study on Analytical Characterization of 2-[2-Thiazolylazol]-5-[(N,N-dicarboxymethyl) amino]-benzenesulfonic Acid and Its Color Reaction with Palladium

报道了新显色剂2－（2－噻唑偶氮）－5－[（N，N－二羧基甲基）氨基]苯磺酸（TADCABS）的合成及其与金属离子的反应，测定了试剂的离解常数．详细讨论了该试剂与Pd2+显色反应的最佳条件，在0.5mol／LHClO4介质中，试剂与钯形成1:1蓝色络合物，其表观稳定常数K稳＝3．96×107.采用双波长法测定，络合物的表观摩尔吸光系数ε（636.4-540.7）=8.05×104，比单波长法测定的灵敏度（ε636.4=5.29×104）提高了52％。反应的灵敏度高，选择性好，可直接用于铂－钯催化剂中微量钯的测定，结果满意．

In this paper, a new color reagent 2-[2-thiazolylazo]-5-[(N. N-dicarboxymethyl) amino]-benzeasulfonic acid (TADCABS) is reported. The acid dissociation constants of the reagent were determined by spectrophotometry. Its color reacions with various metal ions were studied. The optimum reaction conditions of TADCABS with palladium were investigated in detail. A blue complex was formed in 0.5mol/L HClO4 medium, the composition of the complex was l to l and its conditional stability constant was 3.96×107. The apparent molaar absorptivity was 8.05×104·mol-1·cm-1 by dual-wavelength spectrophotometry. The reaction has a high sensitivity and good selectivity. The proposed method was directly used to determine trace palladium in Pt-Pd catalyst and the results were satisfactory.