A new method for radiochemical separation of arsenic from irradiated germanium oxide

Radioarsenic labelled radiopharmaceuticals could be a valuable asset to Positron Emission Tomography (PET). In particular, the long half-lives of 72As (T1/2=26 h) and 74As (T1/2=17.8 d) allow to investigate slow physiological or metabolical processes, like the enrichment and distribution of antibodies in tumor tissue. This work describes the direct production of no-carrier-added (nca) arsenic isotopes *As, with *=71, 72, 73, 74 or 77, the reaction to [*As]AsI3 and its radiochemical separation from the irradiated solid germanium oxide via polystyrene-based solid-phase extraction. The germanium oxide target, irradiated at a cyclotron or a nuclear reactor, is dissolved in concentrated HF and Ge is separated almost quantitatively (99.97%) as [GeF6]2−. [*As]AsI3 is formed by addition of potassium iodide. The radiochemical separation yield for arsenic is >90%. [*As]AsI3 is a versatile radioarsenic labelling synthon.