Since 1996, two new cases were detected in our laboratory for which the elemental concentrations derived from k0 neutron activation analysis seem questionable. These cases concern the inconsistencies observed (1) in the concentration of Ca obtained via 47Ca and 47Sc, and (2) in the concentration of Yb obtained via the 228.5 and 396.3 keV lines of 175Yb. A recommendation is made to re-evaluate the corresponding k0-values or true-coincidence correction factors.
An electronic data base (DB) containing recently evaluated k0 and related data has been developed. The tables composing the DB are relationally linked to support data integrity. The purpose of the DB development is to make an official source of data used for electronic synchronization of the input parameters needed for the k0 methodology, which is developing in numerous laboratories. Such solution saves time when updating, ensures the quality of the primary data and hence of the analysis results, and due to the recording of the updating history preserves traceability of the data in time.
Theko-standardization method is based on analytical constants, which are -line related and the results are calculated from the peak areas of the -ray spectrum. Consequently, prerequisites of this method are the correct identification of the -lines and the avoidance of unresolved peak interferences. Because these problems are already solved with nuclide identification programs, a new variant of theko-method was developed, using the activities of the nuclides instead of the peak areas. We introduced isotope related factors,ki, calculated fromko-factors. The procedure is described and results are compared with those obtained by the -line based method.
Authors:L. C. Oliveira, C. B. Zamboni, and J. Mesa
Neutron activation analysis, using Au as flux monitor, was applied to determine the concentrations of Br, Cl, K and Na in
blood of healthy male and female blood donors, selected from blood banks and hematological laboratories from different regions
of Brazil. The aims of this study were to collect more reference values of the Brazilian population as well as to perform
hematological investigations. The advantages as well as the limitations of using this nuclear procedure are discussed.
Sodium polyacrylate is a superabsorbent polymer (SAP) which is widely used in the manufacturing of disposable diapers. Workplace exposure to respirable dust produced from the handling of these polymers is becoming more of a concern as more data relating occupational exposures to health effects are becoming available. An approach that utilizes the fundamental ion exchange properties of the polymer combined with the sensitivity of instrumental neutron activation analysis has been developed which eliminates interferences from sodium species that are ubiquitous to manufacturing facilities. The technique involves exchanging the sodium that is associated with the polymer with europium and analyzing the exchanged polymer by neutron activation analysis. The technique is simple to run, provides excellent sensitivity and is specific to sodium polyacrylate.
To understand how nutrients are recycled in a particular soil - plant system, we have analyzed the kinetics of the elements Na, Mg, K, Ca, Mn, and Br throughout the life cycle of the plant. The plant sample was collected at 6 different stages of its growth. The effect of V (100 µM) on the element recycling system was also analyzed. The amount of the elements in each tissue of the plant, root, stem, petiole, leaf, and seed, were then determined by neutron activation analysis. The total elemental uptake rapidly increased when the plant developed from the juvenile to the adult phase. More than half of the Mg and Mn in cotyledon was transported to the younger leaves before the cotyledon was shed. From the pattern of movement of each element in plant tissue we have constructed an element recycling model in the soil-plant system. Based on the model, it was found that the amount of K to be a limiting factor for the recycling activity in the system.
Broad scope educational activities at the Neutron Activation Analysis Laboratory (NAAL) associated with the 100 kW University of Florida Training Reactor (UFTR) have been implemented to serve a diverse and multidisciplinary academic clientele to meet a wide spectrum of educational needs for students at all academic levels. Educational usage of the complementary laboratory facilities is described and the importance of such academic experimental experience is emphasized for developing and maintaining a cadre of professionals in the analytical applications of nuclear energy. The synergistic operation of the NAAL and the reactor at the University of Florida to serve as a model worthy of emulation for other similar facilities is emphasized.
Authors:J. Farnum, M. Glascock, M. Sandford, and S. Gerritsen
The elemental composition of 44 human bone samples and 56 soil samples from the Pre-Colombian Tutu site, St. Thomas, Virgin Islands were determined by neutron activation analysis and atomic absorption spectroscopy. Soils from the site were analyzed for the purpose of assessing diagenetic change in the bone samples after deposition. Twenty two elements were observed in the Tutu bones. The compositional data will be considered for use, along with other archaeological information, to aid in dietary reconstruction at the Tutu site.
In short-lived nuclide activation analysis, short-time counting periods, due to rapid radioactive decay, and limited count rates, to avoid dead-time corrections, lead to low counting statistics. This can be improved by cyclic activation, being limited by the sample container strength and by radioactivity build-up. With the new device, longer counting periods and thus better counting statistics, leading to higher accuracy and sensitivity, are achieved by changing the geometry factor during counting for radioactive decay compensation.
Authors:Guisun Zhuang, Yuandi Cheng, Mingguang Tan, Yinson Wang, and Min Zhi
24 male autopsy cases aged 35–60 years have been collected from Shanghai China to study the relationships between human hair and internal tissues. Autopsy samples of hair, kidney-cortex, liver and lung were analyzed. A radiochemical neutron activation analysis (RNAA) based on a simple group extraction scheme was used for measuring the trace elements As, Cd, Hg, Cu and Zn. Zinc diethyldithiocarbamate Zn(DDC)2 and methly isobutyl ketone-iodide have been chosen as reagent. Trace element of Se was determined by instrumental neutron activation analysis (INAA). A SLOWPOKE reactor with a thermal neutron flux of 8·1011 n·cm–2·s–1 and a swimming pool type reactor with a thermal neutron flux of 1·1013 n·cm–2·s–1 were used for short and long irradiation of samples, respectively. The reliability of methods has been checked by analyzing biological standard reference materials Horse Kidney (IAEA H8), Tomato Leaves (NBS 1573) and Human Hair (NIES-5). The analytical results show that toxic elements As, Cd and Hg exist in a larger individual variability than the essential elements of Cu, Se and Zn for each tissue. A linear regression analysis related to the six elements of primary interest for the IAEA Coordinated Research Program (CRP) has been done by a computer program for each pair of hair-tissue. A positive correlation is found between concentration of As in hair and kidney-cortex, the correlation coefficient r is 0.751 (p<0.01). Positive correlations between concentration of Se in hair and liver, kidney-cortex and lung are also observed in this study. It shows that the elements As and Se in hair may be useful indicators for assessing certain internal tissues of normal persons. A comparison of Cd concentration in lung shows a significant difference between smokers and non-smokers. A significant correlation between element Cd and Zn in kidney-cortex is also presented in this paper.