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Journal of Radioanalytical and Nuclear Chemistry
Authors:
E. Tereshatov
,
H. Bruchertseifer
,
M. Voronyuk
,
G. Starodub
,
O. Petrushkin
, and
S. Dmitriev

Abstract  

Isocratic anion exchange separations of Group V elements from solutions containing HF have been considered for the development of Db aqueous phase chemistry experiments. Separation of Nb/Ta from an HF/NH4F system has been demonstrated but has limited utility due to interferences with alpha and spontaneous fission (SF) source preparation. The physical parameters associated with ion exchange chromatography have been optimized for the separation and sequential isolation of Pa, Nb and Ta from mixed HF/HNO3 solutions. A suitable procedure incorporating a series of successive chemical separation techniques, i.e. precipitation and ion exchange chromatography, has been suggested for off-line Db characterization studies.

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Abstract  

Two separation techniques for plutonium determination using IBCS AnaLig® Pu02 molecular recognition technology product (MRT) and extraction chromatography TRU® resin (Eichrom ®Industries) to effectively and selectively separate and recover plutonium were tested. The performance of the methods was successfully tested by analysis of NPL (High Alpha–Beta 2003, 2005) intercomparison sample and radioactive sludge sample from NPP A1 Jaslovské Bohunice with high activities of the plutonium radionuclides. The results obtained for both procedures were compared in terms of activities and recoveries.

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Abstract  

In 1944 Los Alamos National Laboratory (LANL) instituted a program for the collection and analyses of urine samples from individuals working with plutonium. This program has operated continuously for over 60 years. During that time the plutonium bioassay program incorporated advances in urine sample collection, radiochemical separation techniques, alpha-spectroscopy and thermal ionization mass spectrometry measurement techniques as well as cleanroom technology. All of these advances have produced incremental improvements in plutonium detection limits. A chronological description is given of the methodologies used in the plutonium bioassay program at Los Alamos.

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High performance thin layer chromatography (HPTLC) is a frequently used separation technique which works well for quantification of caffeine and quinine in beverages. Competing separation techniques, e.g. high-performance liquid chromatography (HPLC) or gas chromatography (GC), are not suitable for sugar-containing samples, because these methods need special pretreatment by the analyst. In HPTLC, however, it is possible to separate ‘dirty’ samples without time-consuming pretreatment, because disposable HPTLC plates are used. A convenient method for quantification of caffeine and quinine in beverages, without sample pretreatment, is presented below. The basic theory of in-situ quantification in HPTLC by use of remitted light is introduced and discussed. Several linearization models are discussed.A home-made diode-array scanner has been used for quantification; this, for the first time, enables simultaneous measurements at different wavelengths. The new scanner also enables fluorescence evaluation without further equipment. Simultaneous recording at different wavelengths improves the accuracy and reliability of HPTLC analysis. These aspects result in substantial improvement of in-situ quantitative densitometric analysis and enable quantification of compounds in beverages.

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Optimum-performance laminar chromatography (previously known as overpressured-layer chromatography; OPLC) exploits the advantages of the optimum laminar flow of mobile phase obtained by use of pump to introduce the mobile phase to the adsorbent layer in an automated, microprocessor-controlled separation system. The optimized flow profile in OPLC is the basis of the efficiency of this new technique. The attractiveness of OPLC is particularly apparent from the width of the separation surface (large number of samples). OPLC has enabled improvement of the velocity profile with a decrease in eddy diffusion.OPLC can be used for efficient separation of formaldehyde (HCHO) and some betaines, potential HCHO generators, in macroscopic fungi. Endogenous HCHO is determined, after conversion to formaldemethone, and characterized from proton magnetic resonance spectroscopic ( 1 H NMR) and electron-impact mass spectrometric (EIMS) data. The results show that macroscopic fungi contain moderate levels of HCHO compared with, for example, the leaves of certain higher plant species. Among the betaines, l-carnitine and glycinebetaine were identified by matrix-assisted laser-desorption ionization mass spectrometry (MALDI MS), 1 H NMR spectroscopy, and OPLC. Data prove that automated OPLC, a new separation technique, is suitable for efficient separation of natural substances from a large number of samples in one separation; it is, therefore, a prospective complementary methodological direction among separation techniques.

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The BioArena system, which integrates the up-to-date methodology and biological results of bioautography with OPLC as an efficient planar separation technique (compact spots, etc.), is especially suitable for investigating biochemical interactions in an adsorbent bed after chromatographic separation. The first results from BioArena show that formaldehyde (HCHO), which can originate from pathogen cells in some situations, can play a special role in the antibiotic activity of trans -resveratrol. When l -arginine and glutathione were used as endogenous HCHO-capturing molecules in the culture medium the antimicrobial activity of trans -resveratrol on the adsorbent layer decreased substantially. It has been observed that trans -resveratrol generates a time-dependent, and therefore concentration-dependent, duplicate inhibiting effect on the pathogen, and that the BioArena system was suitable for illustration of this new phenomenon. It is probable that this effect occurs as a result of HCHO, with special emphasis on the possibility of interaction between the HCHO and H 2 O 2 of endogenous origin on the adsorbent layer incubated with pathogen cells. It seems that the BioArena system will be an important, indispensable complement to the basic separation technique OPLC.

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Abstract  

Determination of chromium at naturally occuring levels in biological materials requires very low detection limits and dust-free conditions during sampling. These levels are of interest in order to distinguish from enhanced levels which may be carcinogenic. To this purpose a radiochemical separation technique which includes extraction of Cr(VI) into tribenzylamine/chloroform and reextraction into alkaline solution has been improved. Without time-consuming precipitation of BaCrO4 the detection limit has been decreased by a factor of 1.7 compared to earlier, work (to values like 1 ppb) in samples of typically 35 mg by increase of decontamination of65Zn by a factor of up to 1000. Formation of65Zn(OH)2 is shown as the reason for this result. Yield determination was carried out by ICP-AAS-measurements and UV/VIS-spectroscopy. The accuracy of the radiochemical procedure has been proved by analysis of NBS-SRM 1577 Bovine Liver.

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Abstract  

Tin has been determined in biological materials by NAA of the γ-emitting 40-min123Sn and 9,7-min125Sn isotopes at the sub-ppm level. For123Sn, samples are wet-ashed after irradiation, whereas to allow fast radiochemistry for125Sn, the samples are dry-ashed prior to the irradiation. Both separation techniques rely on selective solvent extraction of tin(IV) iodide, and NaI(TI) counting. Comparative analyses of several materials by both methods gave good agreement, indicating that tin is not lost on dry-ashing and that simple dissolution of the ash in an HCl−HI mixture is complete. Results by both techniques are presented for the standard materials Bowen's Kale and NBS Orchard Leaves, and for some other materials.

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Abstract  

At the reactor of the NCSR “Demokritos” epithermal irradiation was used in connection with a loss-free counting technique to investigate rare Neolithic ceramic shards, about 4000 years old, from the Alepotrypa Cave of Diros, Greece. The application of an irradiation time of 30 minutes, the measurements of the samples after less then 24 hours and a counting time of 20 minutes in connection with a loss-free counting unit allowed the determination of 12 elements per sample. The comparison of these rare fine ceramic shards with those of primitive shape showed that both were produced from the same raw materials. Small differences could be explained by a raw material pretreatment. The Neolithic potters were obviously aware of separation techniques in order to obtain fine clay fractions to produce those rare ceramics.

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Abstract  

The classical chemistry like precipitation technique is relevant even in modern days trans-disciplinary research from the view point of green chemistry. A definite demand of no-carrier-added (nca) cadmium tracers, namely, 107,109Cd, has been realized for diverse applications. Development of efficient separation technique is therefore important to address the purity of the tracers for various applications. No-carrier-added 107,109Cd radionuclides were produced by bombarding natural silver target matrix with 13 MeV protons, which gave ~15 MBq/μA h yield for nca 107Cd. The nca cadmium radionuclides were separated from the natural silver target matrix by precipitating Ag as AgCl. The developed method is an example wherein green chemistry is used in trans-disciplinary research. The method is also simple, fast, cost effective and environmentally benign.

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