Radiochemical separation of 76,77Br and 66,67Ga from irradiated ZnSe targets using anion-exchange chromatography

The separation of no-carrier-added (n.c.a.) radiobromine and radiogallium from an irradiated ZnSe target was developed using anion-exchange chromatography. The adsorption behaviour of n.c.a. radiobromine, n.c.a. radiogallium, and macro amounts of zinc and selenium towards the anion-exchange resin Dowex 1 x 10, in Cl- and OH- form, was investigated. Radiobromide was strongly adsorbed on the resin at a low KOH concentration, while n.c.a. radiogallium, zinc and selenium were weakly adsorbed. The adsorbed n.c.a. radiobromine was recovered by 0.2 M H2SO4, followed by addition of KOH, evaporation and redissolution of residue. Finally a K* Br solution was obtained containing about 93 ± 3% of the n.c.a. radiobromine loaded onto the column. The chloride strength in the residual solution (containing n.c.a. radiogallium and macro amounts of zinc and selenium) was increased to 4 M and then loaded onto the Dowex 1 x 10 column in Cl- form. Radiogallium (n.c.a.) was adsorbed while zinc and selenium were not. About 94 ± 2% of the n.c.a. radiogallium loaded on the column was then eluted with 0.1 M HCl. Using this method 76,77Br and 66,67Ga could be obtained in high purity. The radionuclidic purity of the 66Ga/67Ga theragnostic pair is high enough for use in medicine. In the case of the 76Br/77Br pair, however, highly enriched 76Se and 77Se would be needed as target materials, in order to achieve the required radionuclidic purity. (orig.)