INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPIC DETERMINATION OF RARE-EARTH ELEMENTS IN GEOLOGICAL SAMPLES AFTER PRECONCENTRATION BY COUNTERCURRENT CHROMATOGRAPHY .2.

This paper directly links up with Part I [Spectrochim. Acta 48B, 1365 (1993)] which treats the first application of countercurrent chromatog raphy (CCC) for pre-separation of rare earth elements (REE) in rocks. The rapid and reliable separation and pre-concentration of ''light'' R EE and Y can be achieved using a system of 0.5 mol/l di-2-ethylhexylph osphoric acid (D2EHPA) in n-decane-hydrochloric acid of different conc entrations and a planetary centrifuge as a CCC device. However, Tm, nb and Lu are partially retained in the stationary phase. Comparative da ta is presented on three other two-phase liquid systems containing tri octylphosphine oxide (TOPO); D2EHPA and TOPO mixtures and diphenyl(dib utylcarbamoylmethylphosphine)oxide (Ph(2)-Bu(2)) as extractants in ter ms of their ability for whole REE group complete isolation from the ro ck constituents. The partial losses of ''light'' REE (La and Ce) occur red in the system of 0.1 mol/l solution of TOPO in isobutylmethylketon e (IBMK) (stationary phase)-1 mol/l NH4NO3-6 mol/l HCl aqueous solutio ns (mobile phase). Complete isolution of the entire REE group can be r eached in two systems: 0.3 mol/l D2EHPA + 0.02 ml/l TOPO in the solven ts mixture (3:1) of n-decane + IBMK, respectively (stationary phase)-1 mol/l NH4NO3-6 mol/l HCl aqueous solution (mobile phase), and 1.0 mol /l Ph(2)-Bu(2) solution in chloroform (stationary phase)-3 mol/l HNO3 aqueous solution (mobile phase). The D2EHPA + TOPO mixture is recommen ded as more economic and accessible.