Gel chromatographic behaviour of EDTA complexes on Sephadex columns

Abstract

Ethylenediaminetetraacetate complexes of cobalt(II), nickel(II), copper(II), chromium(III), iron(III), cobalt(III) and bismuth(III) were eluted with sodium chloride solution on Sephadex columns. The elution volumes of the complexes (MY n- ) were measured as functions of the concentration and pH of the eluents, sample concentration and gel porosity. The following results were obtained. The concentration dependence of the sample could be classified into two types, M IIY 2- and M IIIY -. The elution volumes were dependent on the concentration of the eluent: in the region of sample concentrations in which the elution volumes of the complexes were maintained constant, these volumes increased with an increase in eluent concentration. The elution volumes were dependent on the pH values of the eluent: the variations in the elution volumes were similar to the variation in the mean charge of the complexes with pH. It seems that the effective radii of the hydrated complexes increase with an increase in the charge of the complexes.