2-(5-羧基-1,3,4-三氮唑偶氮)-5-二乙氨基苯甲酸与锌显色反应的研究

Study on color reaction of 2-(5-carboxy-1,3,4-triazolylazo) 5-diethylaminobenzoic acid with zinc

研究了显色剂2-（5-羧基-1，3，4-三氮唑偶氮）-5-二乙氨基今甲酸（CTZDBA）与锌的显色反应。试剂与Zn^2＋在pH8．0的NH3·H2O—NH4Cl缓冲溶液中形成紫红色络合物，组成比为n（Zn^2＋）：n（CTZDBA）=1：2。络合物的最大吸收波长为545nm，表观摩尔吸光系数ε=4．13×10^4L·mol^-1·cm^-1，Zn^2＋质量浓度在0．08～0．8mg／L范围内符合比尔定律，检出限为1．57×10^-8g／mL。方法不经分离直接测定镁合金和铝合金样品中微量锌，测定结果与认定值相符。

The color reaction of the reagent 2-（5-carboxy-1,3,4-triazolylazo）-5-diethylaminobenzoic acid （CTZDBA） with Zn^2＋ is reported. It is found that this color reagent reacts with Zn^2＋ to form a stable purple red complex （1 ： 2 by mole） in the medium of NH3·H2O-NH4Cl at pH 8.0. The maximum absorption wavelength of the complex is 545 nm, and apparent molar absorptivity is ε=4.13 × 10^4 L ·mol^-1 · cm^-1. Beer＇s law is obeyed in the range of 0.08-0.8 mg/L for zinc, and the detection limit is 1.57 × 10^-8 g/ mL. The method has been applied to the direct determination of trace zinc in magnesium alloy and aluminium alloy samples. The results are in agreement with the certified values.