A RAPID SEPARATION OF SR FROM CA BY SOLVENT-EXTRACTION WITH DICARBOLLIDES IN THE PRESENCE OF EDTA AND POLYETHYLENE GLYCOLS

A typical composition of the solvent extraction system suitable for a rapid separation (3 min shaking) of Ca and Sr (separation factors beta approximately 5000) in both tracer and macroconcentrations involves: organic phase - 0.11 M Li-dicarbollide and 1.65% Slovafol 909 in a mix ture of 40% vol. CCl4 and 60% nitrobenzene; aqueous phase - 0.15M EDTA , 0.1M (H, Li)Ac (acetate buffer), pH approximately 5.2. Replacing Slo vafol 909 (suitable for the preconcentration of RdSr) by polyethylene glycol 400 enhances the distribution ratio D(Sr) by a factor of 7 and beta by a factor of 2. Using Na salts instead of Li ones lowers D(Sr) by a factor of approximately 100 and does not affect the beta value. W hen separating macroamounts of Ca from Sr traces, cam must be exercise d to ensure the desired pH value and free EDTA concentration.