DETERMINATION OF RARE-EARTH ELEMENTS, YTTRIUM, SCANDIUM AND HAFNIUM USING CATION-EXCHANGE SEPARATION AND INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

The determination of low levels of rare-earth elements (REE), Y, Sc and Hf in geological samples has been achieved using minor modifications to established ion-exchange procedures with subsequent analysis by inductively coupled plasma-atomic emission spectrometry (ICP-AES). A lithium metaborate fusion followed by dissolution in dilute hydrochloric acid was used to ensure complete sample decomposition. Sample solutions were loaded onto columns containing AG50W-X8(R) cation-exchange resin, and unwanted elements were removed using elution with 1.75 M HCI followed by 1.75 M HNO3. Almost all potentially interfering elements were eliminated using this procedure (only Ba and Zr remaining), and residual inter-element interferences were easily corrected. By adding a small amount of oxalic acid to the 6 M HNO3 eluant the Hf present in the sample was eluted with the REE, Y and Sc. Analytical data obtained by ICP-AES were judged to be sufficiently accurate and precise ( +/- 5%) for most geochemical applications. Measured detection limits for Y, Sc and Hf were respectively 0.2, 0.1 and 0.2-mu-g g-1 in samples.