Extracted species spectroscopic studies

Cation exchange, solvent extraction and Raman spectroscopic studies of highly acidic zirconium sulfate solutions suggest that these solutions contain a mixture of solution species having from one to four sulfate ligands per Zr atom.153,351 The sulfato-zirconium complexes appear to be somewhat more stable than the analogous hafnium complexes.351... 

Several spectroscopic techniques, namely, Ultraviolet-Visible Spectroscopy (UV-Vis), Infrared (IR), Nuclear Magnetic Resonance (NMR), etc., have been used for understanding the mechanism of solvent-extraction processes and identification of extracted species. Berthon et al. reviewed the use of NMR techniques in solvent-extraction studies for monoamides, malonamides, picolinamides, and TBP (116, 117). NMR spectroscopy was used as a tool to identify the structural parameters that control selectivity and efficiency of extraction of metal ions. 13C NMR relaxation-time data were used to determine the distances between the carbon atoms of the monoamide ligands and the actinides centers. The II, 2H, and 13C NMR spectra analysis of the solvent organic phases indicated malonamide dimer formation at low concentrations. However, at higher ligand concentrations, micelle formation was observed. NMR studies were also used to understand nitric acid extraction mechanisms. Before obtaining conformational information from 13C relaxation times, the stoichiometries of the... 

Gibb, J.O.T., Holmes, E., Nicholson, J.K. and Weeks, J.M. (1997a) Proton NMR spectroscopic studies on tissue extracts of invertebrate species with pollution indicator potential. Comparative Biochemistry and Physiology C, 118, 587-598. 

Investigations may be carried out on the tracer level, where solutions are handled in ordinary-sized laboratory equipment, but where the substance studied is present in extremely low concentrations. Concentrations of the radioactive species of the order of 10 m or much less are not unusual in tracer work with radioactive nuclides. A much larger amount of a suitably chosen non-radioactive host or carrier is subjected to chemical manipulation, and the behavior of the radioactive species (as monitored by its radioactivity) is determined relative to the carrier. Thus the solubility of an actinide compound can be judged by whether the radioactive ion is carried by a precipitate formed by the non-radioactive carrier. Interpretation of such studies is made difficult by the formation of radiocolloids, and by adsorption on glass surfaces or precipitates. Tracer studies provide information on the oxidation states of ions and complex-ion formation, and are used in the development of liquid-liquid solvent extraction and chromatographic separation procedures. Tracer techniques are not applicable to solid-state and spectroscopic studies. Despite the difficulties inherent in tracer experiments, these methods continue to be used with the heaviest actinide and transactinide elements, where only a few to a few score atoms may be available [11]. 

In an analogous way to the measurement of the electronic absorption spectra of cations, those of anions can be obtained. A sputter source has been used to generate the pure carbon anions. In this, a graphite rod is bombarded with cesium ions. The carbon species are formed by sputtering and gas phase processes and the ions produced are extracted for mass-selection. Sufficient ion concentrations have been attained for the spectroscopic studies of carbon anions in the C4 to CJo range. The carbon species are unusual among anions in that they have large... 

Studies of larger species are more complex and the difficulty in the evaluation of their potential surfaces increases with their size. Up to now accurate potentials have been obtained by inversion of spectroscopic data or through high level ab initio calculations " for several triatomic vdW systems. Thus, the interactions for such clusters are available with satisfactory accuracy, which permits the testing of various models of nonadditivity for their ability to reproduce a number of experimental observations. These facts made complexes composed of two rare-gas atoms and a dihalogen molecule especially attractive targets for the study of nonadditive forces. The first attempt to extract information on nonadditive interactions from... 

Time-resolved emission spectroscopy is gaining importance in the study of various chemical aspects of luminescent lanthanide and actinide ions in solution. Here, the author describes the theoretical background of this analytical technique and discusses potential applications. Changes in the solution composition and/or in the metal-ion inner coordination sphere induce modifications of the spectroscopic properties of the luminescent species. Both time-resolved spectra and luminescence decays convey useful information. Several models, which are commonly used to extract physico-chemical information from the spectroscopic data, are presented and critically compared. Applications of time-resolved emission spectroscopy are numerous and range from the characterization of the... 

Isolation from Dosed Crustacea. Metabolites are usually excreted in feces and urine after formation in the hepatopancreas, antennal gland or other sites. The identification of metabolites in crustaceans follows established procedures, i.e., the expected metabolites are predicted from the drug s structure, or from studies with other species, and methods are developed for the extraction and separation of the parent drug and the expected metabolites. Metabolites may then be identified by cochromatography with known metabolite, standards, and by various spectroscopic procedures, such as mass and nuclear magnetic resonance. The major difficulty in working with crustaceans lies in isolating metabolites from hepatopancreas, where most of the metabolites of lipophilic... 

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