Isotope effects of europium in ligand exchange system and electron exchange system using ion-exchange displacement chromatography

The ion-exchange chromatography of europium has been carried out to study the europium isotope effects in a ligand exchange system (LXS) and an electron exchange system (EXS). In both cases highly acidic cation-exchange resin (AG-MP 50) with 100-200 mesh size particles was used. In the case of LXS, where EDTA was chosen as a ligand for Eu2+ ions, the heavier isotope Eu-153 has been enriched at the front boundary of the europium band. Such findings mean that the heavier isotope Eu-153 is preferentially fractionated into the EDTA complex form in the solution phase. In the EXS, where Eu(II)-Eu(III) exchange reaction takes place, the heavier isotope Eu-153 Eu has been observed to be enriched in the front part of the europium band. The result shows that the heavier isotope is preferentially fractionated in the Eu(II) solution phase. The values of the single stage separation coefficients (epsilon=S - 1) of the Eu-153/Eu-151 isotopic pair have been calculated for LXS as 1.48.10(-5) at 80 degrees C and for EXS as 2.13.10(-4) at 60 degrees C. (C) 1998 Elsevier Science B.V. All rights reserved.