本文叙述了在用萃取法系统分离后,用偶氮胂Ⅲ分光光度法测定微量结、铀(Ⅵ)、钍和稀土。从浓度约为4M 的盐酸溶液中,首先将锆萃入噻吩甲酰三氟丙酮(TTA)的二甲苯溶液。然后将铀萃入三正辛胺的二甲苯溶液。接着将钍萃入 TTA 溶液(pH～1.5),最后在 pH～4.7时,将稀土萃入 TTA溶液。在测定前,从有机相中反萃取出每种金属离子。 This paper describes the determination of trace, uranium (Ⅵ), thorium and rare earths by arsenazo Ⅲ spectrophotometry after separation by extraction method. From the hydrochloric acid solution at a concentration of about 4M, the zirconium is first introduced into the xylene solution of the so-benzoyltrifluoroacetone (TTA). Uranium was then extracted into a solution of tri-n-octylamine in xylene. Thorium is then extracted into the TTA solution (pH ~ 1.5) and finally the rare earth is extracted into the TTA solution at pH ~ 4.7. Each metal ion was stripped from the organic phase prior to assaying.