Anomaly of Gd-155 and Gd-157 isotope effects in ligand exchange reactions observed by ion exchange chromatography

The isotope effects of gadolinium in Gd-EDTA ligand exchange system were st udied by means of ion exchange chromatography, The separation coefficients of gadolinium isotopes, Et and the local enrichment factors, beta, were cal culated from the observed isotopic ratios at the front and rear boundaries of the gadolinium adsorption band. Clear mass independent anomalies were ob served in the isotope effects of Gd-155 and Gd-157. The relation between th e isotope effects of gadolinium isotopes, studied by the three-isotope plot and the separation coefficient methods, and the mass of gadolinium isotope s was found to be related to the change in the mean square radius of the nu clear charge distribution parameter, (r(2)), of these isotopes, which sugge sts that the nucleus shape and size highly affect the gadolinium isotope ef fects in chemical exchange reactions.