Chromatography technetium

The ratio of the distribution coefficients of pertechnetate and perrhenate is about 1.6 to 2, comparable to adjacent rare earth metals. Technetium and rhenium may be separated by ion-exchange chromatography. However, efficient separations require some care and tend to be slow. On the other hand, cation exchange resins adsorb technetiiun only to a negligible extent so that pertechnetate can be rapidly separated from cationic elements . 

Sebesta et al. describe a method for the separation of Tc and s + issj g adsorption chromatography using a solution of iV-benzoyl-A-phenylhydroxylamine in chloroform sorbed on Chromosorb W DMCS. The mixture of the radionuclides of technetium and rhenium in 5 M HCIO4 is passed through the coliunn. 

Carvalho has studied the separation of technetium from rhenium by electrophoresis and paper chromatography. Good separations can be obtained by electrophoresis using either alkaline hydra2dne sulfate or a solution of SnClj in hydrochloric acid as electrolytes. Both elements can sufficiently be separated by paper... 

A more efficient method of paper chromatography was developed by Beckman and Lederer making use of the formation of a technetiiun complex with thiourea in nitric acid. TcO is reduced by this reagent, in contrast to ReO". The paper is eluted with 2 N HCl. The R, values of technetium and rhenium have been found to be very different, namely 0.2 and 0.7, respectively. 

Chromatography cyclophosphazenes, 21 46, 59 technetium, 11 48-49 Chromites, as spinel structures, 2 30 Chromium, see Tetranuclear d-block metal complexes, chromium acetylene complexes of, 4 104 alkoxides, 26 276-283 bimetallics, 26 328 dimeric cyclopentdienyl, 26 282-283 divalent complexes, 26 282 nitrosyls, 26 280-281 trivalent complexes, 26 276-280 adamantoxides, 26 320 di(/ >rt-butyl)methoxides, 26 321-325 electronic spectra, 26 277-279 isocyanate insertion, 26 280 substitution reactions, 26 278-279 [9]aneS, complexes, 35 11 atom... 

Radiochemical purity determinations consist of separating the different chemical substances containing the radionuclide. The radiochemical purity of labeled pharmaceuticals is typically determined by paper chromatography (paper impregnated with silica gel or silicic acid). The most frequently used radioisotope is technetium-99m obtained by daily elution with saline... 

Technetium may exist in seven oxidation states. In the " Tc eluate, the chemical species is " Tc(VII)-pertechnetate. The Ph. Eur. states that not less than 95% of the radioactivity is identified as sodium pertechnetate [ Tc] by paper chromatography. 

System III is based on paper chromatography using Whatman I paper strips and acetonitrile-water (1 1) as solvent. Reduced, hydrolized " Tc-technetium (C) remains at the start both Tc-HMPAO complexes (Ah-D) and unbound " Tc-Na-pertechnetate (B) are measured at the solvent front (Ah-Bh-D). 

Radiochemical Purity. The Ph. Eur. (Council of Europe 2005) requires paper chromatography using acetonitrile/water (60 40, v/v) to determine reduced, hydrolized technetium at the start, which should not exceed 2% of the measured radioactivity. For identification of Tc-mertiatide and Tc-Na-pertechnetate, high performance liquid chromatography (HPLC) is recommended. The radiochemical purity of the Tc-MAG3 complex should not be less than 94%. 

Methods Recommended by the Manufacturer. Thin-layer chromatography (TLC) on silica gel reversed phase plates (migration distance 10-15 cm) and acidified methanol-saline is used as solvent for the analysis of three components, namely the " Tc-MAG3 complex (R =0.4-0.5) reduced, hydrolized technetium at the start and unbound 99mTc-Na-pertechnetate at the solvent front. The radiochemical purity of the " Tc-MAG3 complex should not be less than 90%. 

The mass spectrometrie determination of technetium is a highly sensitive and frequently applied method. Tc isotopes fonned upon bombardment of a molybdenum target with 22 MeV protons were identified by mass spectrometry. The technetium fraction was separated and purified by anion exchange chromatography and the isotopes (abundance) c (0.5 %), Tc (56.0 %), Tc (17.3 %), and T c (26.7 %) were detected in about 1 pg technetium on a mass spectrometer for the first time (Fig. 7.1.A). As little as 5 10 g of technetium could be measured by mass spectrometry [491. 

An improved isotope dilution mass spectrometrie technique was developed for the analysis of in environmental samples, is isolated from the sample, after spiking with Tc as a yield tracer, by ion-exchange chromatography and solvent extraction. Technetium is then concentrated onto a pair of anion exchange beads of 0.3 mm in diameter. Determination of 10 g of technetium was achieved through the enhanced ionization efficiency afforded by the resin bead source [50]. Spark source mass spectrometry was... 

Dry distillation and gas phase separation of technetium oxides from oxides of rhenium, osmium, iridium, and ruthenium by temperature-programmed gas chromatography using O2 as reactive gas was reported [109]. Furthermore, the separation of technetium chloride (TeCU) from volatile chlorides of numerous elements by thermo-chromatography combined with complex formation was investigated. The separation tube had a temperature gradient from 600 to 25 °C and was coated with KCl, CsCI, NaCl, and BaClj [HOj. 

In addition, thin-layer chromatography was employed for the separation of technetium and molybdenum. Neutron-irradiated molybdate was separated from produced 99niTc04 on cellulose MN 300 using butanol saturated with I M HCl [180]. Molybdate was identified in pertechnetate solutions by means of thin layers of silica gel or AI2O3 with mixtures of 1 M HCl/methanol or 1 M HCI/ethanol as solvents. ITic TCO4 spot revealed a higher mobility than the M0O4 spot [181]. 

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