Determination of rare earth elements in uranium and zirconium: Analytical applications of X-ray excited optical fluorescence spectra. I

A rapid and quantitative technique for the analysis of gadolinium, dysprosium, europium and samarium in uranium and zirconium is described. The method, X-ray excited optical fluorescence, uses high-energy X-rays to excite the rare earth impurities in appropriate matrices. The excited rare earth impurities fluorescence with simple line emission spectra which can be used for quantitative measurements. The rare earths were coprecipitated with thorium carrier from an acid solution as ThF4-NH4F and thus separated from large amounts of uranium or zirconium. The separated thorium carrier were purified and finally converted to thorium oxide. Terbium is added as a "control" on the recovery of other rare earths. These oxides were then irradiated with X-ray and emitted fluoreces spectra were used for the determination of rare earth elements. Added terbium was also used as an "internal standard" on the intensity measurements. The limit of detection for gadolinium and europium was 5 ppb and that for dysprosium and samarium was 20 ppb.