Study of Benzothiazolylazo-5-dimethylaminobenzoic Acid and Its Derivate as Analytical Reagents Ⅰ.
TONG Shenyang, JIN Xia (Department of Chemistry)
2-[2-(6-Bromo-benzothiazo]ylazo)]-5-dimethylaminobenzoic acid was synthesised and its acid-base equilibrium was studied. A spectrophotometric method has been developed for the determination of copper with Br-BTAMB as a sensitive reagent. Br-BTAMB reacts instantly with copper in a aqueous alcohol solution to form a 1:1 blue complex (λ =654nm) over pH range 4-5.5 and the complex is stable for more than 24 h. The apparent molar absorptivity of the complex is 6.4×104 at 654nm. It follows Beer's law in the range from 0 to 18μg/25ml of copper. The method can be applied to the determination of copper in natural water.