A simple column chromatographic method was developed to isolate 77As (94 ± 6% (EtOH/HCl); 74 ± 11 (MeOH)) from germanium for potential use in radioimmunotherapy. The separation of arsenic from germanium was based on their relative affinities for different chromatographic materials in aqueous and organic environments. Using an organic or mixed mobile phase, germanium was selectively retained on a silica gel column as germanate, while arsenic was eluted from the column as arsenate. Subsequently, enriched 76Ge (98 ± 2) was recovered for reuse by elution with aqueous solution (neutral to basic). Greater than 98% radiolabeling yield of a 77As-trithiol was observed from methanol separated [77As]arsenate [17].

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Arsenic-72 ((72)As) and (77)As have nuclear properties useful for positron emission tomography (PET) and radiotherapy, respectively. The thiophilic nature of arsenic led to the evaluation of dithioarylarsines for potential use in radiopharmaceuticals. Several dithioarylarsines were synthesized from their arylarsonic acids and dithiols and were fully characterized by NMR, ESI-MS, and X-ray crystallography. This chemistry was translated to the no-carrier-added (nca) (77)As level. Because arsenic was available at the nca nanomolar level only as [(77)As]arsenate, this required addition of an aryl group directly to the As to form the [(77)As]arylarsonic acid. The [(77)As]arsenate was reduced from (77)As (V) to (77)As (III), and a modified Bart reaction was used to incorporate the aryl ring onto the (77)As, which was followed by dithiol addition. Various modifications and optimizations resulted in 95% radiochemical yield of nca [(77)As]p-ethoxyphenyl-1,2-ethanedithiolatoarsine.

Summary An anion exchange method was developed to separate selenium and arsenic for potential utility in a 72Se/72As generator. The separation of the daughter 72As from the 72Se parent is based on the relative acid-base behavior of the two oxo-anions in their highest oxidation states. At pH 1.5, selenate is retained on strongly basic anion exchange resin as HSeO4− and SeO42−, while neutral arsenic acid, H3AsO4, is eluted.

Novel, natural abundance metal disulfide targets were irradiated for 1h with a 10µA proton beam in a small, medical cyclotron. Osmium disulfide was synthesized by simple distillation and precipitation methods while MoS2 and WS2 were commercially available. The targets dissolved under mild conditions and were analyzed by γ-spectroscopy. Production rates and potential applications are discussed, including target recovery and recycling schemes for OsS2 and WS2.