Evaluation of a wet chemistry method for isolation of cyclotron produced [At] astatine

Balkin, E. R.*; Hamlin, D. K.*; Gagnon, K.*; Chyan, M.-K.*; Pal, S.*; Watanabe, Shigeki; Wilbur, D. S.*

A "wet chemistry" approach for isolation of At from an irradiated bismuth target is described. The approach involves five steps: (1) dissolution of bismuth target in conc. HNO; (2) removal of the HNO by distillation; (3) dissolution of residue in 8 M HCl; (4) extraction of At from 8 M HCl into DIPE; and (5) extraction of At from DIPE into NaOH. Results from 55 "optimized" At isolation runs gave recovery yields of approximately 78% after decay and attenuation corrections. An attenuation-corrected average of 263 mCi in the target provided isolated (actual) yields of 163 mCi of At. A sixth step, used for purification of At from trace metals, was evaluated in seven runs. In those runs, isolated At was distilled under reductive conditions to provide an average 718% recovery. RadioHPLC analyses of the isolated At solutions, both initial and after distillation, were obtained to examine the At species present. The primary species of At present was astatide, but astatate and unidentified species were also observed. Studies to determine the effect of bismuth attenuation on At were conducted to estimate and attenuation factor (1.33) for adjustment of At readings in the bismuth target.