RESUMO
Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml(-1), modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 Å. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride.
Assuntos
Cromatografia com Fluido Supercrítico/métodos , Nitrogênio/química , Boroidretos/química , Boroidretos/isolamento & purificação , Dióxido de Carbono/química , Cromatografia com Fluido Supercrítico/instrumentação , Magnésio/química , Pressão , TemperaturaRESUMO
Component fractions of 99mTc(NaBH4)-HEDP mixtures, isolated by anion exchange high performance liquid chromatography (HPLC), have been evaluated as myocardial infarct imaging agents in two animal models. Results from both the isoproterenol-induced myocardial infarction model, and the heat-induced myocardial necrosis model, show that the several HPLC isolated components exhibit significantly different abnormal/normal heart uptake ratios. In addition, the HPLC isolated component of shortest chromatographic retention time exhibits a higher abnormal/normal heart uptake ratio than does 99mTc(Sn)-PyP, the current agent of choice for clinical myocardial infarct imaging.
Assuntos
Boroidretos , Cromatografia Líquida de Alta Pressão , Ácido Etidrônico , Infarto do Miocárdio/diagnóstico por imagem , Pirofosfato de Tecnécio Tc 99m , Tecnécio , Animais , Boroidretos/isolamento & purificação , Combinação de Medicamentos , Feminino , Cintilografia , Ratos , Ratos Endogâmicos , Tecnécio/isolamento & purificação , Polifosfatos de EstanhoRESUMO
Anion exchange high performance liquid chromatography has been utilized to separate the component Tc-HEDP complexes of "carrier added" as well as "no carrier added" 99mTc(NaBH4)-HEDP reaction mixtures. The chromatographically separated "carrier added" Tc-HEDP components exhibit distinctly different biodistributions which are directly related to the chromatographic characteristics of the individual components. The Tc-HEDP complexes with shortest retention times, and therefore the lowest negative "charge density" have the maximum uptake on the bone, minimum uptake in the kidney, and fastest blood clearance.
