Ion chromatographic techniques were investigated for the separation and the quantitative determination of some rare earth elements (REEs) in monazite and xenotime minerals. The influences of selected eluents containing complexing acids including oxalic and alpha-hydroxy isobutyric acid (alpha-HIBA) on the retention and hence the separation efficiency of REEs was studied. Different variables affecting the separation of different REEs such as pH, type, and concentration of the mobile phase were investigated. Gradient elution, using an advanced gradient pump, was controlled automatically by the Dionex AI-450 computer software. Separation of REEs was carried out using an Ion Pac CS5A column followed by a post column derivatization reaction with 4-(2-pyridylazo)resorcinol (PAR) and UV-VIS spectrophotometric detection. Mineral dissolution was carried out using sulfuric acid. A comparative evaluation of REE distribution in monazite and xenotime minerals using both ion chromatography (IC) and inductively coupled plasma atomic emission spectrometric (ICP-AES) techniques was carried out.
A procedure was developed for preparing high radiochemical purity 99m Tc-valsartan with yield of 98%. The complex was prepared by mixing of valsartan with SnCl 2 .2H 2 O solution and the pH of the mixture was adjusted to 8 then mixed with a freshly eluted 99mTc O4-(~400 MBq), shacked at room temperature for 30 min. The radiochemical yield and purity of the labeled product were determined individually by HPLC, paper chromatography and paper electrophoresis. Biodistribution studies were carried out in normal Albino Swiss mice at different time intervals after administration of 99m Tc-valsartan. The labeled compound cleared from the systematic circulation within 2 h after administration, and the majority of organs showed significant decrease in the uptake of 99m Tc-valsartan. The heart uptake of 99m Tc-valsartan was sufficiently high for using this agent as myocardial imaging agent.
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