Cyclic Instrumental Neutron Activation Analysis Research Articles

A pilot study to measure levels of selected elements in Thai foods by instrumental neutron activation analysis

A pilot study was carried out to evaluate the scope of instrumental neutron activation analysis (INAA) for measuring the levels of selected elements in a few commonly consumed food items in Thailand. Several varieties of rice, beans, aquatic food items, vegetables and soybean products were bought from major distribution centers in Bangkok, Thailand. Samples were prepared according to the protocols prescribed by the nutritionist for food compositional analysis. Levels of As, Br, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, and Zn were measured by INAA using the irradiation and counting facilities available at the Thai Research Reactor with the maximum in-core thermal neutron flux of 3 × 1013 cm−2 s−1 of the Thailand Institute of Nuclear Technology in Bangkok. Selenium was determined by cyclic INAA using the Dalhousie University SLOWPOKE-2 Reactor facilities in Halifax, Canada at a thermal neutron flux of 2.5 × 1011 cm−2 s−1. Both cooked and uncooked foods were analyzed. The elemental composition of food products was found to depend significantly on the raw material as well as the preparation technique.

Transfer time optimization of a rapid cyclic instrumental neutron activation analysis for trace element detection

A rapid pneumatic transfer system for the cyclic instrumental neutron activation has been indigenously designed and installed. The system enables the detection of short-lived thermal and epithermal neutron activated nuclides. Interfacing between gamma spectrometry and other components of the system is achieved through two programmable logic controllers. Optimization of the transfer time for trace element detection was thoroughly studied. Different factors affecting the reduction of transfer time were analyzed. Transfer time of the irradiating capsule under current operating conditions is about 700 ms. The setup will be used for both cyclic and pseudo-cyclic as well as instrumental neutron activation analysis.

Practical aspects of instrumental neutron activation analysis with the Miniature Neutron Source Reactor (MNSR)

Instrumental neutron activation analysis (INAA) often relies on reactions withthermal neutron fluxes of ≤1012cm-2s-1 like with the Chinese madeMiniature Neutron Source Reactor (MNSR). Next to the obvious advantages of a small reactor,there are the inherent limitations of intermittent operation, the low flux and its eventualdecrease over the working period and the necessity of using cyclic INAA rather than singlerabbit irradiations. They bear on the precision and accuracy of results. This paper dealswith the use of the MNSR for routine INAA in terms of the capacity of existing and eventualadditional irradiation facilities and with the elimination of systematic biases and theoptimization of precision. A survey of eventual applications is added.

Determination of selenium in Canadian food items by cyclic instrumental neutron activation analysis.

Instrumental neutron activation analysis (INAA) and pseudocyclic INAA (PCINAA) have been used to determine the selenium content of a variety of Canadian food items. Use of the 162-keV gamma ray of short-lived 77mSe in INAA allowed relatively simple and rapid determinations and was suitable for many of the foods. PCINAA was found to give lower detection limits and was used for the low-selenium food samples. Both internal and external quality assessments were used to evaluate and assure the accuracy and precision of the methods developed.

Automation of a pneumatic system by controlling a microcomputer equipped with a custom add on board for neutron activation analysis

An automated sample transfer system associated with a 3 × 592 GBq AmBe neutron source has been constructed at the Ankara Nuclear Research and Training Center (ANRTC) for Instrumental Neutron Activation Analysis (INAA) and Cyclic Instrumental Neutron Activation Analysis (CINAA). The pneumatic transfer system is controlled by an IBM PS/1 personal computer which is equipped with a custom add-on board for relevant hardware and control software written in Turbo Pascal. The system computer interactively works with a Multichannel Analyzer (MCA) for proper data acquisition. The sample transfer system also runs manually. The design and performance of the hardware and software are discussed.

The analysis of human nails for 24 elements via k0 and cyclic neutron activation analysis

The possibility of using human nails as a monitor for the exposure from occupation is presented. The concentrations of 24 elements in the human toenails from 129 construction workers were determined by cyclic instrumental neutron activation analysis (CINAA) and k 0-standardization method. For CINAA, samples were irradiated and counted for three cycles with one day decay between cycles, and then the spectra were summed. The detection limits of fluoride, scandium, and silver were improved by a factor of two over conventional single irradiation method when CINAA was applied. Twenty two elements were determined using the k 0 method. The accuracy and precision of the k 0 method are discussed in this paper.

Determination of fluoride in human nails via cyclic instrumental neutron activation analysis

The role of fluorine in human health has become somewhat controversial. It is widely accepted as protective against dental caries, may be protective against osteoporosis, and has been very conservatively implicated with osteosarcoma in male rats. In this study, we repot on the development of a neutron activation analysis method and its application to the analysis of human nails. We have found that toenails collected in population-based epidemiology studies apparently reflect fluoride intake.

Fluorine determination in diet samples using cyclic INAA and PIGE analysis

Fluorine is an important trace element for life and human well-being. Food, in general, provides about 40 percent of the fluorine intake in the human body. In order to measure fluorine levels in human diet samples, Instrumental Neutron Activation Analysis (INAA) and Proton Induced Gamma-ray Emission (PIGE) analysis were used. Reactions19F(n,γ)20F and19F(n, p)19O were employed for determination of the fluorine concentration using a reactor neutron spectrum and epithermal neutrons. Corrections were made for the sodium matrix interference caused by the23Na(n, α)20F threshold reaction in the case of reactor neutron cyclic activation analysis and for the oxygen interference via18O(n, γ)19O reaction when using the epithermal cyclic NAA method. The fluorine content of the diet samples was also determined by PIGE analysis making use of the resonance reaction19F(p, αγ)16O at 872 keV. Cyclic Neutron Activation Analysis (CNAA) when combined with mass fractionation was found to be the most suitable for determination of low concentration of fluorine, through the19F(n, γ)20F reaction with a detection limit of 2.2 ppm in Bowen's Kale elemental standard.

Evaluation of homogeneity of selected reference materials for selenium by cyclic neutron activation analysis

The homogeneity of four reference materials was evaluated for Se by cyclic instrumental neutron activation analysis (CINAA). The relative standard deviation for Se measurements at ppb levels by CINAA was <12% for NIST Wheat Flour (SRM 1567) in 5–10 mg samples, while it was <11% for Chinese Hair (HH−CH-1), <13% for IAEA Animal Muscle (H-4) and 25% for IAEA Animal Blood (A-13) in 50 mg samples. The highest relative subsampling uncertainties were observed in the mass range of samples ≤50 mg for Chinese Hair, ≤100 mg for Wheat Flour and Animal Muscle and ≤300 mg for Animal Blood. The results of a one-way analysis of variance indicate that all reference materials above these mass ranges are adequately homogeneous with respect to Se distribution. Our data suggest that these materials, except Animal Blood, can be used as reference standards for Se in Quality assurance programs well below the sample masses re commended by the issuing agencies.

Statistical Discrimination of Flat Glass Fragments by Instrumental Neutron Activation Analysis Methods for Forensic Science Applications

Abstract Instrumental neutron activation analysis (INAA) and cyclic INAA (CINAA) techniques were used for the discrimination of flat glass fragments. Employing short irradiation, delay, and count times, sample test portions of 100 µg and 1 mg (INAA) or 1 and 5 mg (CINAA) were considered. A statistical model was used to assign the elemental variation among glasses to different experimental factors; by advanced statistical methods elemental differences between specific glasses can be identified. Analysis and comparison of float glass panes produced by two major Canadian manufacturers were also performed; the two were readily differentiated, primarily on the basis of their aluminum levels.

Determination of selenium in duplicate diets of residents of Pinhel, Portugal, by neutron activation

A rapid cyclic instrumental neutron activation analysis (CINAA) method has been used to determine the selenium content of 27 duplicate diet samples from each of the 27 districts surrounding Pinhel, Portugal. The accuracy and precision of the CINAA method have been evaluated by analyzing certified reference materials and observed to be within +/- 5-10% for samples containing at least 40 ppb of selenium. The detection limit has been found to vary between 26-42 ppb selenium depending on the sample composition. The average daily dietary intake has been calculated as 37 micrograms of selenium per day.

Determination of sampling constants for selenium in biological reference materials by neutron activation

A cyclic instrumental neutron activation analysis method has been used to calculate sampling constants and to evaluate homogeneity for Se in five biological reference and certified reference materials, namely NRC lobster hepatopancreas (RM TORT-1), IAEA horse kidney (RM-H8), and NIST bovine liver (SRM-1577a), oyster tissue (SRM-1566) and mixed diet (RM-8431). The between-weight-range heterogeneity has been observed to be no greater than the within-weight-range heterogeneity. The subsampling standard deviation (Ss) has been found to be less than the measurement standard deviation (Sm) for H-8 (>5 mg sample) and TORT-1 (>50 mg). For 1577a, Ss is almost equal to Sm; while Ss is 2–3 times higher than Sm for the other two materials. The sampling constants varied between 0.04 and 3.0 g for four materials while the mixed diet had a value of 31 g.

Determination of trace elements in food by neutron activation analysis

Neutron activation analysis (NAA) methods have been developed for the determination of major, minor and trace elements in duplicate diets and individual food items. These include a cyclic instrumental NAA (CINAA) method for measuring Se content through its short-lived nuclide77mSe; epithermal INAA (EINAA) for I and As; conventional INAA for Br, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Sc, Sn and Zn; combination of EINAA and INAA for Al; radiochemical NAA (RNAA) for As, Au, Co, Cu, Fe, Hg, Mo, Sb, Se and Zn; and preconcentration NAA (PNAA) for U and Th. Accuracy of measurements have been evaluated by analyzing a number of biological and diet reference materials. Multielement concentrations of diets and foods have been measured by these methods.

Determination of selenium in individual food items using the short-lived nuclide77mSe

The selenium content of a variety of food items representing a normal hospital diet has been determined by cyclic instrumental neutron activation analysis (CINAA) through the 162-keV gamma-ray of the77mSe nuclide. The CINAA method is very simple and rapid. It involves irradiation of a sample for 20 s, decay for 20 s, and counting for 20 s. The precision of the method has been significantly improved by recycling the samples up to 4 times. The accuracy has been evaluated by analyzing a number of certified reference materials of varied selenium levels.

The usefulness of the advance prediction computer program in INAA studies

In this paper, the nature of the instrumental neutron activation analysis (INAA) Advance Prediction Computer Program (APCP) is described, as well as its purposes, capabilities, and the wealth of valuable output information it provides. Recent and present extensive applications of the APCP to both reactor-flux and isotopic-source INAA of a great variety of biological, environmental, and geochemical reference materials are summarized. Other completed forms of the APCP that also include fission-spectrum and 14 MeV fast-neutron products are mentioned, as well as a recently completed form of the APCP for high-intensity reactor pulses, and present efforts to develop APCP's for cyclic INAA and prompt-gamma INAA are discussed.

Determination of selenium, arsenic, iodine and bromine in fish, plant and mammalian oils by cyclic instrumental neutron activation analysis

AbstractThe concentrations of arsenic, selenium, iodine and bromine in a series of fish, plant and mammalian oils have been determined by cyclic instrumental neutron activation analysis (CINAA). Crude fish oils contain between 0.047 and 0.151 μg Se g−1, 2.36–14.5 μg As g−1, 2.36–9.63 μg Br g−1 and 0.97–4.76 μgI g−1. Seal oil contains the same four elements, but at levels below the lower end of the fish oil ranges. Iodine, bromine and arsenic were not detected in rape‐seed or soybean oils and the concentration of selenium varied from &lt; 0.010 to 0.042 μg g−1. The levels of selenium, iodine and bromine are reduced markedly by hydrogenation of the menhaden oils. The CINAA method yielded results which were in agreement with pub‐lished values obtained by other methods. The technique was rapid, requiring minimal sample manipulation, and was essentially free from interferences.

The effect of sample matrix on selection of optimum timing parameters in cyclic neutron activation analysis

Cyclic instrumental neutron activation analysis can be used to improve detection limits for short-lived nuclides. The detection limit for a given nuclide is a function of the activity arising from the sample matrix and the various timing parameters used in the analysis. An easily operated computer program, based on the cyclic activation equation, has been developed to estimate theoretically the optimum timing parameters for a number of short-lived nuclides in four different types of simulated sample matrix. The computed results are discussed with reference to the change in maximum sensitivity when optimum conditions are not used, and a comparison is made with the experimentally determined results for the measurement of selenium in NBS Bovine Liver.

Cyclic neutron activation analysis of biological and metallurgical samples

A rapid pneumatic transfer cyclic system for use with the SLOWPOKE reactor has been designed which allows detection of nuclides with half-lives as short as 0.8 s. Reliable reproducibility is achieved with a 1 s transfer period from reactor to detector. Both accuracy and relative standard deviation are significantly improved with some matrices as the number of cycles is increased but the gains in detection limits increase with the square root of the number of cycles. Cyclic instrumental neutron activation analysis has been successfully applied to the determination of Ag, F, Hf, Pb, Rb, Sc, and Se in a variety of biological and metallurgical matrices. The detection limits ranged from 0.01 to 2.2 ppm for all elements studied except Pb.