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Summary  

The thermal neutron prompt gamma-ray activation analysis (PGAA) facility, operated by the US Food and Drug Administration and National Institute of Standards and Technology Center for Neutron Research, has been redesigned to lower background radiation levels and improved analytical capabilities. Analysis of 22 element standards and food and botanical certified reference materials revealed significant sensitivity increases and lower limits of detection for H, B, C, N, Na, Al, P, S, Cl, K, Ca, Fe, and Cd. Mass fractions for these elements, as well as Mg, Al, Si, Ti, Mn, Fe, Cu, I, Zn, Sm, and Gd, were determined for 6 dietary supplements.

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A fast pneumatic transfer facility was installed in Nuclear Engineering Teaching Laboratory (NETL) of the University of Texas at Austin for the purpose of cyclic thermal and epithermal neutron activation analysis. In this study efforts were focused on the evaluation of cyclic epithermal neutron activation analysis (CENAA). Various NIST and CANMET certified materials were analyzed by the system. Experiment results showed 110Ag with its 25 s half-life as one of the isotopes favored by the system. Thus, the system was put into practical application in identifying silver in metallic ores. Comparison of sliver concentrations as determined by CENAA in CANMET certified reference materials gave very good results.

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Abstract  

Instrumental neutron activation analysis (INAA) was applied to assess element concentrations in eleven samples of mineral supplements/multivitamins acquired in drugstores and pharmacies in São Paulo city, SP, Brazil. Concentrations of Ca, Co, Cr, Cu, Fe, K, Na, Se and Zn were determined. A comparison was made between the results obtained with the labels of the mineral supplents. Certified reference materials, NIST SRM1400 Bone Ash and NIST SRM 1633b Coal Fly Ash were analyzed for quality control of the analytical results.

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A study was carried out in Havana City using lichen as monitor of air pollution. The concentration of several trace elements (Ca, Mn, Fe, Ni, Cu, Zn, Sr, Cd, Pb) in a total of 225 samples was determined by Total Reflection X Ray Fluorescence (TRXRF), Flame Atomic Absorption Spectroscopy (FAAS) and Anodic Stripping Voltammetry (ASV). In addition several Biological Certified Reference Materials (CRM’s) were analyzed in order to assess the analytical performance of the results. In general a relatively good agreement was found among the techniques. No significant differences were found between the obtained results and the certified reference values.

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Neutron activation analysis was applied to assess trace element concentrations in brain tissues from normal (n = 21) and demented individuals (n = 21) of both genders aged more than 50 years. Concentrations of the elements Br, Fe, K, Na, Rb, Se and Zn were determined. Comparisons were made between the results obtained for the hippocampus and frontal cortex tissues, as well as, those obtained in brains of normal and demented individuals. Certified reference materials, NIST 1566b Oyster Tissue and NIST 1577b Bovine Liver were analyzed for quality of the analytical results.

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Abstract  

The analysis of impurities in uranium matrices is performed in a variety of fields, e.g., for quality control in the production stream converting uranium ores to fuels, as element signatures in nuclear forensics and safeguards, and for non-proliferation control. We have investigated the capabilities of time-of-flight ICP-MS for the analysis of impurities in uranium matrices using a matrix-matched method. The method was applied to the New Brunswick Laboratory CRM 124(1–7) series. For the seven certified reference materials, an overall precision and accuracy of approximately 5% and 14%, respectively, were obtained for 18 analyzed elements.

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The paper presents the results of radiological investigation of several mushroom samples collected in the fall of 2004 in different parts of Europe. The work was performed in order to support decision making to develop and produce a certified reference material for quality assurance of radionuclide measurements in environmental samples. The levels of 137Cs in mushrooms varied widely ranging from 0.6 to 4300 Bq/kg on dry mass basis, while those of natural 40K were relatively constant. In one sample 60Co of unknown origin was detected (25±2 Bq/kg dry mass), while 90Sr concentrations were usually below the detection limit (<150 mBq/kg dry mass).

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Abstract  

An automated delayed neutron counting (DNC) system has been developed at the Royal Military College of Canada (RMC) to enhance nuclear forensics capabilities pertaining to special nuclear material analysis. The system utilises the SLOWPOKE-2 Facility at RMC as a neutron source and 3He detectors. System control and data acquisition occur through a LabVIEW platform. The time dependent count rate of the delayed neutron production has been examined for 235U, using certified reference materials. Experimental validation according to ISO 17025 protocols suggests typical errors and precision of −3.6 and 3.1%, respectively, and a detection limit of 0.26 μg 235U.

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Summary  

Neutron activation analysis technique, using Au as flux monitor, was applied to determine element concentrations of Ca, K, Na, Mg, Mn and Sr in certified reference material (NIST 1400 Bone Ash). The results were compared with those using comparative INAA and they were compatible. The same results were obtained using the recommended k 0 factors, in order to obtain the activation cross section as input in concentration for the same reference material. Some applications in the health area aiming clinical evaluation in bone samples of medium and small-sized animals were performed and the viability of using this methodology was discussed.

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Summary  

The k 0-method in INAA has been used at CENA/USP Brazil for analyzing geological and biological materials. With the acquisition of a well-type detector, it was realized that the true-coincidence effects, originally corrected by semi-empirical procedures with the in-house k 0-software (Quantu-INAA), would affect the accuracy of results. Thus, new coincidence correction algorithms were developed, based on a theoretical equation for obtaining the correction factors. Validation of the algorithms was performed by analysis of plant certified reference materials.

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