Selenium-72 formation via natBr(p,x) induced by 100MeV Protons: Steps towards a novel 72Se/72As generator system

Chromatographic separation of selenium and arsenic: A potential 72Se/72As generator

“…Arsenic-76 (t 1/2 = 1.0942 d) used as an As tracer in batch studies was produced at the MURR via the 75 As (n, γ) 76 As reaction of an encapsulated 75 As (as nat As 2 O 3 ) target, which was dissolved in 1 M NaHCO 3 . A mixture of radioactive selenium ( 72,75 Se), arsenic ( 72,73,74 As), and sodium ( 22 Na) in 0.1 M HCl and ~3 M NaCl (from processing) [22], produced by the irradiation of natural NaBr targets with 72–92 MeV protons at the Los Alamos National Laboratory – Isotope Production Facility (LANL-IPF), was evaluated for producing a 72 Se/ 72 As generator. On receipt, the sample contained 19.34 μCi of 22 Na, 2.8 μCi of 72 As (with 72 Se in equilibrium), 62.51 μCi of 73 As, 56.26 μCi of 74 As, and 35.24 μCi of 75 Se as determined by gamma spectroscopy (HPGe).…”

“…Cross-section data suggest that these are the best production methods [15,19,20]. Alternatively natural NaBr targets irradiated with higher energy protons (72–92 MeV) generate Se radioisotopes ( 72 Se, 73 Se, 75 Se) with fewer by-products than higher energy reactions [7,21,22]. The higher beam currents available (average of 101.4 μA) at the Los Alamos National Laboratory Isotope Production Facility (LANL-IPF) make this a viable route although radioselenium impurities are generated [22].…”

“…Alternatively natural NaBr targets irradiated with higher energy protons (72–92 MeV) generate Se radioisotopes ( 72 Se, 73 Se, 75 Se) with fewer by-products than higher energy reactions [7,21,22]. The higher beam currents available (average of 101.4 μA) at the Los Alamos National Laboratory Isotope Production Facility (LANL-IPF) make this a viable route although radioselenium impurities are generated [22]. Any of these routes will produce 72 Se for generator development, with the 72 Se generally separated from its target as Se(0) [15,17] or Se(IV) [16,18,20].…”

“…Selenium-72/Arsenic-72 ( 72 Se/ 72 As) radionuclide generators have been proposed in the literature [14], however complex separation/isolation methods are required. Separation of the daughter from the parent can occur via repeated distillation of “grown-in” 72 AsCl 3 from carrier added 72 Se stock solutions [16,21]; electroplating of 72 Se as Cu 2 Se on Cu backings [23], solvent extraction [22] or solid phase extraction of 72 Se [17,24]. However, with the exception of the solid phase extraction method, the reported methods require laborious and/or significant handling.…”

“…However, with the exception of the solid phase extraction method, the reported methods require laborious and/or significant handling. The solid phase approach as reported in the literature is limited to very small dimensions (500 μL cartridge volume, few μCi of 72 Se activity) involving reagents such as HF, requires Se in its elemental state under an inert atmosphere to prevent oxidation, and scale up to clinically useful 10 mCi batches may not be feasible [17,22,24]. …”