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目前有许多测定铬的方法,但对于对-磺基苯偶氮变色酸吸光光度法测定三价铬的方法未见报道。对-磺基苯偶氮变色酸是一种较灵敏的偶氮类显色剂,简称SPADNS。该试剂能与钍形成紫色络合物,可做钍的检出剂或显色剂。本文研究了该试剂作为显色剂与Cr(Ⅲ)反应的最佳条件以及络合物的组成等诸项试验,试验发现,Cr(Ⅲ)与该显色剂在酸性介质中可形成蓝紫色络合物,该反应的灵敏度和选择性均较好,用于测定钢铁中铬,得到较好的结果。
There are many methods for the determination of chromium, but the method for the determination of trivalent chromium by p-sulfophenylazo chromotropic acid spectrophotometry has not been reported. Para-sulfophenylazo chromotropic acid is a more sensitive azo-type developer, referred to as SPADNS. The reagent can form a purple complex with thorium, do thorium detector or developer. In this paper, the best conditions for the reagent to react with Cr (Ⅲ) and the composition of the complex were studied. It was found that Cr (Ⅲ) and the developer could form blue-violet in acidic medium Complex, the reaction sensitivity and selectivity are better, for the determination of chromium in steel, get better results.