Isotope effects in the V(IV)-malate complex formation system

摘要

Cation-exchange displacement chromatography of VO2+ was carried out for studying vanadium isotope fractionation in the malate complex formation system. After the chromatographic elution, the heavier isotope V-51 was found to be enriched at the front boundary of the VO2+ band, which indicates that the heavier isotope is preferentially fractionated into the malate complex in the aqueous solution phase. The isotope separation coefficient epsilon (= alpha - 1) for V-50 and V-51 was obtained as 1.0 X 10(-4) for the malate system at 298 K. This value is smaller than the ones for UO22+ and CU2+ in the same ligand systems. Binuclear complex species in UO22+ and Cu2+ solutions may be attributed to the larger isotope effects in the complex formation system. Through comparison of the reported separation coefficient values of E per unit mass differences (epsilon/DeltaM) of the alkali, alkaline earth and transition elements in the complex formation systems, it is suggested that the stronger the complex of the concerned element, the more the isotopic fractionation can obtain. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 31]