SEPARATION OF SOME TRACE RARE-EARTHS FROM URANIUM BY 2-STEP LIQUID-LIQUID-EXTRACTION AND ESTIMATION BY ICP-AES

Trace amounts of rare earths, Ce, Sm, Eu, Gd, Dy, Er, Yb, and Y separated from nuclear grade uranium were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The separation of the trace rare earths was done by a two-step liquid-liquid extraction procedure. The first step involved the separation of the rare earths by complexing with tributylphosphate in CC1(4) medium. The second step employed tri-n-octylphosphine oxide which removed the final traces of uranium from the aqueous phase. The two-step procedure yielded recoveries for the trace rare earths in the range 90-103 %. The detection limits obtained by the ICP-AES method for the rare earths in aqueous solution ranged between 0.1 and 9.5 ng/ml.