INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPIC DETERMINATION OF RARE-EARTH ELEMENTS IN GEOLOGICAL SAMPLES AFTER PRECONCENTRATION BY COUNTERCURRENT CHROMATOGRAPHY .1.

Countercurrent chromatography (CCC) was applied to group pre-separatio n of rare earth elements (REE) in rocks. A 0.5 mol/l solution of di-2- ethylhexylphosphoric acid (D2EHPA) in n-decane as stationary phase, an d aqueous HCl solution as mobile phase were used. Experimental conditi ons were found for quantitative separation of REE from the rock consti tuents that interfere with their inductively coupled plasma atomic emi ssion spectrometry (ICP-AES) determination. The complete pre-separatio n procedure takes 40 min at a mobile phase pumping rate of 2 ml/min. I nterelement and off-peak background corrections were applied to compen sate for the contributions of mutual spectral interferences to the ana lyte line and background intensities. Standard reference rock material s and samples of different composition with well known REE contents we re analysed. The data obtained are in good agreement with certified an d previously determined values, except for ''heavy'' REE such as Tm, Y b and Lu.