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光度法测定锌合金、黄铜中铝已为工厂试验室普遍采用。我们曾对偶氮染料的铬变酸2R和TBA-偶氮胂光度法测定铝作了研究。邻羧基苯偶氮变色酸是变色酸的单偶氮衍生物,试剂结构简单、合成容易,用该试剂光度法测定锌合金和黄铜中铝至今尚未见文献报道。本文研究了该显色反应,发现铝与邻羧基苯偶氮变色酸在pH 5.1～5.9的微酸性介质中可形成1:1的紫红色络合物,络合物的最大吸收峰位于580nm,表观摩尔吸光率为2.8×10~4,是测定铝较灵敏的显色剂,50ml中Al≤10μg符合比耳定律。我们用该试剂测定锌合金和铝黄铜中铝,结果令人满意。
Spectrophotometric determination of zinc alloy, brass, aluminum has been commonly used in factory laboratories. We have studied the azo dye chromogenic acid 2R and TBA-arsenic photometric method for the determination of aluminum. Carboxyl azo chromotropic acid is a monoazo derivative of chromotropic acid. The reagents are simple in structure and easy to synthesize. The determination of zinc alloy and brass in aluminum by this reagent has not been reported until now. In this paper, the color reaction was studied. It was found that the 1: 1 fuchsine complex can be formed by aluminum and phthalidochloric acid in slightly acidic media at pH 5.1-5.9. The maximum absorption peak of the complex is at 580 nm, The apparent molar absorptivity is 2.8 × 10 ~ 4, which is a sensitive reagent for determination of aluminum. In 50ml, Al≤10μg complies with Beer’s law. We used this reagent to determine the zinc alloy and the aluminum in aluminum brass, with satisfactory results.