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-separation 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, and aqueous HCl solution as mobile phase were used. Experimental conditions were found for quantitative separation of REE from the rock constituents that interfere with their inductively coupled plasma atomic emission spectrometry (ICP-AES) determination. The complete pre-separation procedure takes 40 min at a mobile phase pumping rate of 2 ml/min. Interelement and off-peak background corrections were applied to compensate for the contributions of mutual spectral interferences to the analyte line and background intensities. Standard reference rock materials and samples of different composition with well known REE contents were analysed. The data obtained are in good agreement with certified and previously determined values, except for ''heavy'' REE such as Tm, Yb and Lu.