RESUMO
Positron-emitting 72As is the PET imaging counterpart for beta-emitting 77As. Its parent, no carrier added (n.c.a.) 72Se, was produced for a 72Se/72As generator by irradiating an enriched 7°Ge metal-graphite target via the 70Ge(α, 2â¯n)72Se reaction. Target dissolution used a fast, environmentally friendly method with 93% radioactivity recovery. Chromatographic parameters of the 72Se/72As generator were evaluated, the eluted n.c.a. 72As was characterized with a phantom imaging study, and the previously reported trithiol and aryl-dithiol ligand systems were radiolabeled with the separated n.c.a. 72As in high yield.
Assuntos
Arsênio/isolamento & purificação , Radioisótopos/isolamento & purificação , Geradores de Radionuclídeos , Compostos Radiofarmacêuticos/isolamento & purificação , Radioisótopos de Selênio/isolamento & purificação , Germânio/química , Germânio/isolamento & purificação , Germânio/efeitos da radiação , Humanos , Isótopos/química , Isótopos/isolamento & purificação , Isótopos/efeitos da radiação , Imagens de Fantasmas , Tomografia por Emissão de Pósitrons , Ensaio Radioligante , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/químicaRESUMO
Studies have shown that information related to the presence of low-molecular-weight metabolites is frequently lost after deproteinization of complex matrices, such as blood and plasma, during sample preparation. Therefore, the effect of several deproteinization reagents on low-molecular-weight selenium species has been compared by species-specific isotope labeling. Two isotopically enriched selenium tracers were used to mimic models of small inorganic anionic (77Se-selenite) and organic zwitterionic (76Se-selenomethionine) species. The results presented here show that the use of a methanol-acetonitrile-acetone (1:1:1 v/v/v) mixture provided approximately two times less tracer loss from plasma samples in comparison with the classic procedure using acetonitrile, which may not be optimal as it leads to important losses of low-molecular-weight selenium species. In addition, the possible interactions between selenium tracers and proteins were investigated, revealing that both coprecipitation phenomena and association with proteins were potentially responsible for selenite tracer losses during protein precipitation in blood samples. However, coprecipitation phenomena were found to be fully responsible for losses of both tracers observed in plasma samples and of the selenomethionine tracer in blood samples. This successfully applied strategy is anticipated to be useful for more extensive future studies in selenometabolomics.
Assuntos
Proteínas Sanguíneas/análise , Plasma/química , Traçadores Radioativos , Radioisótopos de Selênio/análise , Selênio/análise , Selenometionina/análise , Proteínas Sanguíneas/isolamento & purificação , Espectrometria de Massas , Peso Molecular , Selênio/química , Selênio/isolamento & purificação , Radioisótopos de Selênio/química , Radioisótopos de Selênio/isolamento & purificação , Selenometionina/química , Selenometionina/isolamento & purificaçãoRESUMO
An anion exchange method was developed to separate selenium and arsenic for potential utility in a (72)Se/(72)As generator. The separation of the daughter (72)As from the (72)Se 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 SeO4(2-), while neutral arsenic acid, H3AsO4, is eluted.
