同一份称样中微量铀和钍采用三辛基氧膦(TOPO)萃取光度法连续测定,一般文献中所列步骤均较烦琐。本文采用TOPO一次萃取,有机相用0.1mol/L H_2SO_4反萃取钍,经洗涤后直接用5-Br-PADAP-F-光度法测定铀;反萃取液则在0.5mol/L HCl介质中,采用偶氮氯膦mV(CPA-mN)-溴化十六烷基三甲铵(CTMAB)-二苯胍(DPG)多元络合物法测定钍。钍络合物的λ_(max)=670nm,ε_(670)=1.6×10~5,钍量在0—12.5μg/25mL范围内符合比尔定律,组成比Th(Ⅳ):CPA-mN=1:5;铀络合物的λ_(max)=575nm,ε_(575)~5=7.8×10~4,铀量在0—17 The same sample of uranium and thorium in the sample using trioctylphosphine oxide (TOPO) extraction spectrophotometry continuous determination of the general steps listed in the literature are more cumbersome. In this paper, TOPO was used for the first extraction, thorium was stripped with 0.1 mol / L H 2 SO 4 in the organic phase and uranium was directly measured by 5-Br-PADAP-F-photometric method after washing. The stripped solution was treated with 0.5 mol / L HCl Determination of Thorium with m - Chlorophosphonazo mV (CPA - mN) - Cetyltrimethylammonium Bromide (CTMAB) - Diphenylguanidine (DPG) Complex. Λ max of the thorium complex is 670 nm and ε 670 is 1.6 × 10 5. The Beer’s law of thorium content is in the range of 0-12.5 μg / 25 mL. The composition ratio Th (Ⅳ): CPA-mN = 1 : 5; λ_ (max) of uranium complex = 575nm, ε_ (575) ~ 5 = 7.8 × 10 ~ 4,