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Abstract  

Molecular activation analysis based on biological separation techniques combined with instrumental neutron activation analysis (INAA) was applied to study the distribution patterns of 24 elements, including essential and unknown trace elements in the liver organelles. Concentrations of As, Au, Co, I, Mg, Mo, Sb, Sc, Se and Th were found to be the highest in nuclei and mitochondria, while those of Br, Cl, Cs, Cu, K, Na, Rb and V were found to be in cytosol. Concentrations of Al, As, Au, Ba, Fe, I, Sb were found to be the lowest in cytosol. The element As was mainly present in the nuclear fraction, where its concentration was two to four times higher than that in other fractions. Ca and Fe were highly enriched in the microsomal fraction.

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Abstract  

Production of radioactive scandium by irradiating natural titanium metal in Pakistan Research Reactor-1 was evaluated. The production rate of 47Sc and other radioactive scandium was estimated. High specific activity 47Sc can be produced by irradiating enriched 47Ti in sufficient quantities needed for therapeutic applications. A new separation technique based on column chromatography was developed. Neutron irradiated titanium was dissolved in hydrofluoric acid, which was evaporated and taken in distilled water. The resulting solution was loaded on silica gel column. The radioactive scandium comes out first and the inactive titanium is removed with 2 M HCl. More than 95% radioactive scandium was recovered, while chemical impurity of titanium determined by optical emission spectroscopy was less than 0.01 μg/mL in final product.

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Abstract  

The method for laboratory separation of85Kr from the atmosphere based on cryogenic adsorption technique has been developed. The physical parameters of the separation equipment have been chosen with respect to the properties of scintillation crystal CaF2/Eu/ used as a detector of85Kr. The apparatus contains dry-ice, silicagel and molecular sieve traps for the removal of H2O and CO2. The activated charcoal columns are used for concentration and preparation of krypton sample. The separation technique is supplemented by gas-chromatographic determination of total amount of separated krypton. The apparatus enables processing of up to 20 m3 of air with the krypton yield about 80%. The relative errors of the determination of the concentration of85Kr in the air by elaborated method is about 5%.

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Abstract  

In connection with the application of the uranium series method for the dating of fossil bones, separation techniques were developed for the isolation of uranium and thorium from a bone matrix. These separations were achieved on columns of the strongly basic anion exchange resin Dowex 1, using media of hydrochloric acid (for the isolation of uranium) and nitric acid (for the isolation of thorium). For uranium and thorium, yields of about 100% and about 70%, respectively, were obtained. The measurement of the α-activities was carried out following the electrolytic preparation of thin-layers of uranium and thorium on stainless steel discs. The α-spectrometry was done by means of Si-surface barrier detectors. Results are presented for a sample of snake-bones found in an Austrian cave.

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Abstract  

Due to the essential functions of selenium-containing enzymes and the relationships between changes in the selenium status and diseases, the determination of the element and its compounds is of great interest. Radiotracer studies with 75Se have been valuable tools in selenium research. NAA and ICP-MS allow both total element and stable isotope measurements. ICP-MS in conjunction with chromatographic separation techniques and gel electrophoretic procedures coupled with scanning methods such as XRF, PIXE and laser ablation ICP-MS have been used in the determination of the selenium compounds. In this survey the application of these methods in selenium research is discussed with the help of examples on the regulation of the selenium metabolism and the detection and investigation of novel selenium-containing proteins.

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Abstract  

Solvent extraction is a separation technique suitable for the treatment of used nuclear fuel. Two immiscible phases are contacted and the metals of interest are extracted from one phase into the other, most often using so called extractants. One group of extractants is the bis(triazine)-bipyridine (BTBP) type molecules. These molecules have been developed within EU research programs for the separation of actinides from lanthanides. During such an extraction process, the components of the two phases will be exposed to ionizing radiation, since the used fuel contains many highly radioactive species. Radiolytic reactions can alter the chemistry of the extracting system, and affect the metal extraction by degradation of the extractant and the formation of degradation products. In this paper the effect of irradiation with alpha particles and gamma rays, respectively, has been studied for one of the BTBP type molecules, C5-BTBP.

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Determination of trace elements in petroleum by neutron activation analysis

I. Determination of Na, S, Cl, K, Ca, V, Mn, Cu, Ga and Br

Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Shah
,
R. Filby
, and
W. Haller

Abstract  

Using thermal neutron activation and a large-volume high-resolution Ge(Li) γ-ray spectrometer, the feasibility of the determination of the concentrations of Na, S, Cl, K, Ca, V, Mn, Cu, Ga, and Br in crude oils has been demonstrated. This instrumental method, which requires neither a chemical separation technique nor pre-concentration or post-concentration of trace elements by ashing, eliminates many inherent errors associated with chemical determination. The method is sensitive, precise and suitable for routine analysis. Fast neutron (n, p) and (n, α) reactions do not appreciably interfere and where necessary corrections may be applied. Loss of volatile elements, e.g. chlorine and bromine, due to recoil during irradiation is negligible.

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Abstract  

Knowledge of the oxidation state distribution of plutonium in natural waters is necessary in modeling its behavior in environmental systems. The redox speciation of plutonium is complicated by such effects as hydrolysis, complexation, disproportionation, solubility, and redox interchange reactions. The insolubility of Pu(OH)4 is often the limiting factor of the net solubility of plutonium in oxic natural waters where Pu(V)O 2 + is the most stable oxidation state. Perturbations to the oxidation state speciation due to the complexation chemistry of the different oxidation states of plutonium and to the insolubility of plutonium(IV) in neutral aquatic systems are discussed. The merits and limitations of some chemical separation techniques used to study redox speciation of plutonium are presented, and recommendations made for obtaining reliable oxidation state distribution data.

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Abstract  

A brief history of the development and some of the first uses of “atom-at-a-time” techniques to investigate the chemical and nuclear properties of the actinide and transactinide elements are presented. The currently known transactinides (all elements with Z > 103) were discovered using physical (nuclear) techniques rather than chemical separation techniques because of their short half-lives and low production rates and the difficulty in accurately predicting chemical properties of the heaviest elements because of relativistic effects. Some of the constraints on systems suitable for such studies and whether these tracer-scale results can be extended to the macro-scale are discussed. The relevance and importance of the methods and their potential for application to some current problems such as nuclear forensics and proliferation and environmental concerns are considered. The value of graduate research utilizing such techniques in helping to attract and educate the next generation of nuclear scientists is highlighted.

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Summary

Enantiomer separations have been one of the most important and, simultaneously, one of the most difficult to accomplish analytical (and technological) tasks, present at the top of separation scientists' agenda since the early sixties of the last century. Awareness of their importance has been awakened by an infamous case of the racemic drug thalidomide, a widely advertised sedative drug which had unexpected teratogenic activity in pregnant women that resulted in thousands of ‘flipper babies’ born in the late fifties and the early sixties in many countries around the world. Since that time, separation scientists have developed numerous methods for enantiomer separation, basically by use of gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrophoresis (CE). In this respect, planar chromatography has remained to a large extent an undervalued enantiomer separation technique, despite separation performance sufficient to separate a pair of enantiomers. The large number of GC, HPLC, and CE enantiomer separation strategies and methods developed are evidence that — once confronted with this particular and no doubt very important challenge — instrumental chromatographic techniques have lost if not face, then, to a large extent, their reputation as robust, universal, and efficient separation tools. In these circumstances, planar chromatography on silica gel seems a very promising and tempting alternative, basically because of the advantageous properties of microcrystalline silica gel and the 2D effective diffusion available only in planar chromatographic mode. Enhancement of the enantiomer separating power of the silica gel by simple mechanical impregnation with a properly chosen chiral selector, and additional coupling of this with efficient instrumental detection (e.g. densitometric, DAD, or mass spectrometric) can yield in a simple, robust, and universal tool for separation of enantiomers comparable with the long-established chromatographic enantiomer-separation techniques. In this mini review, favourable preconditions for silica-gel-based planar chromatographic separation of enantiomers which can elevate planar chromatography to the status of leading tool for separation of enantiomers are discussed. Further improvements which can enhance the enantiomer separation performance of chiral planar chromatography are also indicated.

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