十二烷基苯磺酸钠增溶-镁试剂Ⅰ褪色光度法测定痕量硒

在pH 2.0的KCl-HCl缓冲溶液中,硒(Ⅳ)与镁试剂I和十二烷基苯磺酸钠(SDBS)反形成三元络合物,使镁试剂I褪色,据此建立了褪色光度法测定硒的新方法。最大褪色波长为452 nm。体系的褪色程度与硒(Ⅳ)浓度在0.01~0.12μg/mL范围呈线性关系,检出限为1.9μg/L。测定2.5μg硒(Ⅳ)时,0.1 mg Fe3+、Cr2O72-,0.05 mg MnO4-和大量的常见离子可允许存在,因此一般样品可以不经分离直接测定。方法用于硫酸厂和电厂废水中硒的测定,相对标准偏差小于1.8%(n=5),加标回收率分别为99%和103%。

Fading spectrophotometric determination of trace selenium with magneson Ⅰ using sodium dodecylbenzene sulfonate as solubilizer

In KCl-HCl buffer solution at pH 2.0, Se (Ⅳ) reacted with magneson I and sodium dodecyl-benzene sulfonate (SDBS) to form a ternary complex, resulting in fading of magneson I.Accordingly, a new fading spectrophotometric method was developed for the determination of selenium.The maximum fading wavelength located at 452 nm.The fading degree of the system was linear with the concentration of Se(Ⅳ) in the range of 0.01 - 0.12 μg/mL.The detection limit was 1.9 μg/L.For determination of 2.5 μg of Se (Ⅳ), 0.1 mg of Fe~(3+), 0.1 mg of Cr_2O_7~(2-), 0.05 mg of MnO_4~- and a lot of common ions were tolerable.Thus, common samples could be determined directly without separation.The method has been applied to determine selenium in waste water samples from sulfuric acid plant and power plant, with the relative standard deviation below 1.8 % (n = 5) and the standard addition recovery of 99 % and 103 % respectively.