Post-elution concentration of 99TcmO4- by a single anion exchanger column: II. Preparation and evaluation of jumbo alumina column chromatographic generator for 99Tcm.

Abstract

We report on the preparation and evaluation of a large size (jumbo) alumina column (approximately 40 g, 90 x 20 mm) chromatographic generator and post-elution concentration of 99Tcm using a single column of a weak anion exchanger. The generator was eluted with approximately 40 ml of a modified single salt buffer solution of 1:1 v/v 0.025 M or 0.05 M NH4OAc:0.7 M AcOH. This eluate was then passed through a small column of DEAE cellulose, a common weak anion exchanger, to trap 99TcmO4-, which was recovered by elution in 6 ml of normal saline. This amounts to a 5- to 7-fold increase in radioactive concentration (RAC) of 99Tcm, when compared to the RAC on direct elution with normal saline from the same jumbo alumina column generator. The overall yield of 99Tcm was in the range of 70-90%. 99Mo breakthrough was 10(-3)-10(-4)%, radiochemical purity was > 98%, and chemical purity, in terms of Al and Mo content, < 10 ppm each. The compatibility of pertechnetate obtained by this method for preparing 99Tcm labelled formulations such as Tc-MDP and 99Tcm-ethyl cysteinate dimer was found to be satisfactory. These promising results open up the feasibility of using (n, gamma) 99Mo adsorbed on a large (40-60 g) alumina column as a relatively more user-friendly source of 99Tcm in comparison to methyl ethyl ketone extraction, and as a producer-friendly process in comparison to the zirconium molybdate gel method.