对氨基苯磺酸—a-萘胺测定微量铬(Ⅵ)

The Determination of Trace Chromium(Ⅵ) by P-aminobenzene Sulfonic Acid and ａ-Naphthylamine Spectrophotometric Method

基于铬 ( )在稀盐酸介质中氧化盐酸羟胺产生亚硝酸根 ,而亚硝酸根与对氨基苯磺酸重氮化后可与 α-萘胺偶联产生粉红色偶氮染料 ,提出了分光光度法测定铬 ( )的新方法。研究表明 :铬( )浓度在 0～ 0 .0 0 1 g/L内服从比耳定律 ,其线性相关系数 γ为 0 .99998,表观摩尔吸光度 ε52 0 为3.442 4× 1 0 4 L· mol-1· cm-1。所拟方法可用于水样中微量铬 ( )的测定 ,结果令人满意。

A new spectrophotometric method for the determination of chromium(Ⅵ) has been developed. In HCl medium,the chromium(Ⅵ ) oxidizes hydroxylammonium chloride to form nitrite,which produces a pink azo dye when reacting with p- aminobenzene sulfonic acid andα- naphthylamine.Beer's law is obeyed in the range of 0～ 0 .0 0 1 g/L with the absorptivityε52 0 =3.442 4× 1 0 4 L· mol-1· cm-1and relative coeffi- cientγ=0 .99998.The proposed method has been applied to the determination of chromium(Ⅵ) in water samples and tap water with satisfactory results.