核纯铀中14种稀土杂质的萃取色层－光谱测定

采用我院研制的ＣＬ－５２０８和ＰＭＢＰ萃淋树脂，萃取色层分离－光谱法测定了核纯铀中１４种微量稀土元素。文中较详细地比较了不同类型激发光源和光谱仪器的稀土测定下限，以及样品激发保护气氛和电极构型对稀土测定灵敏度的影响。以取样量１ｇ计算，１４种稀土杂质定量测定下限在０．０００５—０．０４μｇ／ｇ。化学分离回收率在８５％－１１３％。方法相对标准偏差（ＲＳＤ）５％－２２％。样品对照结果基本符合。方法灵敏，操作简便，便于厂矿推广应用。

DETERMINATION OF TRACE RARE EARTH ELEMENTS IN NUCLEAR GRADE URANIUM BY SPECTROCHEMICAL METHOD AFTER EXTRACTION CHROMATOGRAPHIC SEPARATION

In this article,a new method is described for the determination of the trace amounts of 14 REE impurities (La, Ce, Pr, Nd, Sin, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu and Y) in nuclear grade uranium by spectrochemical method after extraction Chromatographic separation. The detection limits of REE are compared among atmosphere (air and protective atmosphere),excitation sources (A. C. arc and ICP)and spectrograph (1, 2, 3, 4m grating and prism) in different conditions.The samples were dissolved in concentrated HNO3 and the elements of RE were separated from uranium and other impurity elements of non--RE by chromatographic procedures. CL-5208 levextrel resin was used as the fixed phase and 6mol/l- HCl as eluent in the first chromatographic procedure; CL--PMBP levextrel resin was used as the fixed phase and REE were adsorbed by pH=5. 5 2mol/L acetic acid--acetate as fluid phase and were eluted with 0. 1mol/L HCl at a flow rate of 0. 5mL/min in the second chromatographic procedure. The resulting concentrated eluent was mixed with varying quantities of calcium as the carrier and transferred to the pre-treated concave graphite electrodes. During A. C. arc (7A)excitation for 40 sec.,a gas mixture of argon and oxygen (3: 1) with a flow rate of 3 L/min was passed through the cyclonic gas chamber of silica glass,in which the electrodes were located.The chemical recoveries of REE are 85%--113%. The detection limits of REE are0. 5--40ppb. The RSD is less than 22 %. This method is simple,rapid and can be widely used in routine analyses.