1-(5-溴-2-吡啶偶氮)-2-萘酚-6-磺酸与铜(Ⅱ)显色反应及其应用的研究

Color Reaction of Copper with 1- (5-Bromo-2-pyridylazo)-2-naphthol-6-sulphonic Acid and Its Application

本文研究了1-（5-溴-2-吡啶偶氮）-2-萘酚-6-磺酸（5-Br-PAN-S）与铜（Ⅱ）的显色反应。实验表明，铜（Ⅱ）与5-Br-PAN-S形成的络合物的组成比随pH值的变化而变化，在pH2．0～6．0，形成1：1络合物，最大吸收峰为558nm，表观摩尔吸光系数为2．30×104Lmol-1cm-1，在pH9．0形成1：2络合物，其最大吸收峰为551nm，表观摩尔吸光系数为3．92×104Lmol-1cm-1，并求得铜（Ⅱ）与5-Br-PAN-S络合物的lgβ1＝14．23，铜量在0～35μg／25ml，（pH2．0）范围内服从比耳定律。用本法测定了柑桔根、叶中铜的含量，结果满意。

Color reaction of copper with 1- (5-bromo-2-pyridylazo)-2-naphthol acid (5-Br- PAN-S) has been studied. The molar ratio of copper(pH2～6) with 5-Br-PAN-S is 1: 1, λmax= 558nm. The apparent molar absorptivity of this chelate is 2. 30×104Lmol-1 cm -1 At pH9. 0, the molar ratio of copper with 5-Br-PAN-S is 1: 2, λmax= 551nm,and its apparent molar absorptivity is 3. 92× 104 Lmol -1cm-1.Bear's law is observed in the range of 0～ 35μg/25mL, (pH = 2 ). This method has been applied to the determination of trace copper in the roots and leaves of orange trees with satisfactory results.