Separation scheme for selective and quantitative isolation of cobalt from neutron-irradiated biological materials by ion exchange and extraction chromatography

Highly reliable radiochemical separation scheme for selective and quantitative isolation of trace amounts of cobalt from neutron-irradiated biological materials was elaborated. The method consists in wetashing of the sample with HNO3+HClO4 (1:1) mixture plus vanadium salt (oxidation catalyst), removal of silica by evaporation with HF and separation of cobalt from accompanying ions successively on 3 columns with Dowex 1-X8[Cl-] from 0,5 M HCl, Dowex 1-X8[Cl-] from 8 M HCl+2 M MgCl2 and tri-n-octylphosphine oxide (TOPO) supported on styrene-divinylbenzene copolymer, from 7 M HCl solution, respectively. Cobalt of very high radiochemical purity is finally recovered in 1.2 M HCl solution with practically 100% yield. The separation scheme is universally applicable, to biological samples of both animal and plant origin and was devised to become an integral part of the very accurate (definitive) method of cobalt determination by neutron activation analysis (NAA). Preliminary results on Co-determination by NAA in some certified reference materials confirmed high reliability of the devised separation scheme