Neutron Activation Analysis Method Research Articles

Analysis of essential elements in Pito-a cereal food drink and its brands by the single-comparator method of neutron activation analysis.

Instrumental neutron activation analysis using the single-comparator method has been used for the multielement determination of essential elements in two main types of Pito brewed locally in Ghana. The precision and accuracy of the analytical method was validated and found to be within 10%. In all, eight different brands of Pito depending on the type of cereal crop used in brewing were analyzed for 13 different elements (Al, As, Ba, Cl, Co, Cu, Fe, K, Mg, Mn, Na, Si, and Zn). It was observed that all brands were particularly enriched in nutrient elements Cl, Mg, and K. The rest were generally found in varying concentrations. As these elements are bioavailable in natural form, perhaps in combination with organic constituents, they are likely to be easily digested and assimilated by the human body. Arsenic, a toxic element, was found in insignificant amounts suggesting that it was within safe limits.

The NAA method at Polytechnique Montreal: an efficient alternative way to use the k 0 NAA models

At Ecole Polytechnique Montreal, the philosophy in performing neutron activation analysis (NAA) is long-term and application oriented. Thinking long-term implies a good understanding of the fundamentals of the method, of the samples, of the tools, reactor and detectors, and there must be constant innovation that is experimentally validated with extensive measurements. Application oriented means a NAA method developed to provide users with fast, sensitive, accurate and reliable analyses for various types of materials. This philosophy dictates the manner in which the developments in the areas of NAA software, peak-area calculation, dead-time correction, detection efficiency model, k 0 and Q 0 values, neutron moderation and neutron self-shielding are carried out. This paper presents a survey of the Laboratory’s methodology, reviewing a few of its unique features such as detector efficiency calibration and sample related perturbations of the neutron activation. These features are used as examples to provide the reader with an understanding of the philosophy and the evolution of the NAA method at Ecole Polytechnique.

Mineralogical and Geochemical Characteristics of the Human Body Ash Residue

The article is devoted to the element composition of the human body ash residue of some Russian cities. It presents the element composition of the human body ash residue, the distribution of elements in the ash residue depending on age and sex. The specific elements of different cities, showing the possible influence of the environmental conditions on the element composition of the human body ash residue. The main objective of this paper is to study the element composition of the human body ash residue and determine the regional characteristics. The methods of instrumental neutron activation analysis and inductively coupled plasma mass spectrometry were applied, an electronic microscope being used as a tool. The result of the research is 63 elements identified within in the human body ash residue. The issue is topical as it expands the knowledge of rare and radioactive elements within the human body and contributes to medicine, for example, by identifying the chemical elements to be included in a person's diet.

Ecological Dangers of Chemical Contamination of Urban Areas Soils: Casestudy of Tomsk

The elemental composition of soils in Western Siberia industrial center – Tomsk city is studied. The content of 28 elements in soils of the four administrative districts is determined by the instrumental neutron activation analysis method. The value of calculated total pollution index indicates a high degree of soil contamination, and dangerous levels of human health risk. The main contributors to the total pollution index value are elements: Tb, Br, Sb and Ta. The districts were ranked by the accumulation level of some elements, and it is shown that increased concentration values are confined to industrial enterprises and fuel cycle. The specificity of city districts soil cover is the increased values of relative to the city average values of several elements contents: Kirovsky district- Na and Ba, Oktyabrsky - Hf, Sc, Tb, Sm, La, Ce, Yb, Lu, and Br, Leninsky - Ca, Rb, Sr. The main sources of chromium and barium in the Tomsk city environment are analyzed.

Trace element determination in high-purity aluminum clad samples by k 0-based internal monostandard instrumental neutron activation analysis

The k0-based internal monostandard instrumental neutron activation analysis (IM-INAA) method was applied for quantification of trace impurities in seven high purity aluminum samples used as fuel cladding in a research reactor. Samples along with BCS CRM 182 (Si–Al alloy) were irradiated in high flux reactor neutrons for 10–15 h. In situ detection efficiency, needed in concentration calculation ratio by IM-INAA, was obtained using gamma rays of activation products produced in the samples. Elemental concentration ratios obtained with respect to Fe (used as internal monostandard) were converted to absolute concentrations by determining concentration of Fe by relative method of NAA. Concentrations of ten trace elements (Sc, Cr, Co, Zn, Ga, La, Ce, Sm, W and Hf) including major element Fe were determined in this work. The method used is non-destructive in nature and does not need multielement standards. Results of IM-INAA were compared with those obtained by relative method of INAA and inductively coupled plasma atomic emission spectrometry (ICP-AES). Details of methodologies and results obtained by all methods are discussed and compared in the paper.

Evaluation of INAA–anticoincidence counting for measuring nanogram levels of vanadium in relatively high-salt nutritional reference materials

An instrumental neutron activation analysis method in conjunction with anticoincidence counting (INAA–AC) gamma-ray spectrometry was developed for the determination of ppb levels of V in biological, mostly nutritional, reference materials containing varying amounts of salt. The method involved irradiation in the Dalhousie University SLOWPOKE-2 reactor facility at a fission neutron flux of 5 × 1011 cm−2 s−1 for 1 min, decay for 1 min, and counting for 10 min. In order to fully investigate the extent of improvement that can possibly be obtained for V determination by INAA–AC, a theoretical term called the analytical figure of merit was developed and applied to 16 National Institute of Standards and Technology and International Atomic Energy Agency reference materials. The overall background around the 1,434.1-keV photopeak of 52V was reduced by a factor of 5–10 for several materials in the anticoincidence counting mode. The detection limits were lowered by factors of 3–5 in INAA–AC (0.61–9.4 μg kg−1) compared to conventional INAA (1.9–79 μg kg−1) in samples with varying ratios of Na/V (0.24–1,000), Cl/V (0.12–1,827), Al/V (7.45–115) and Mn/V (1.84–66.9) making rapid and reliable V measurements possible at sub-ppb levels without any chemical separation.

Improvements in an in vivo neutron activation analysis (NAA) method for the measurement of fluorine in human bone

We previously published a method for the in vivo measurement of bone fluoride using neutron activation analysis (NAA) and demonstrated the utility of the technique in a pilot study of environmentally exposed people. The method involved activation of the hand in an irradiation cavity at the McMaster University Accelerator Laboratory and acquisition of the resultant γ-ray signals in a ‘4π’ NaI(Tl) detector array of nine detectors. In this paper we describe a series of improvements to the method. This was investigated via measurement of hand simulating phantoms doped with varying levels of fluorine and fixed amounts of sodium, chlorine and calcium. Four improvements to the technique were tested since our first publication. The previously published detection limit for phantom measurements using this system was 0.66 mg F/g Ca. The accelerator irradiation and detection facilities were relocated to a new section of the laboratory and one more detector was added to the detection system. This was found to reduce the detection limit (possibly because of better detection shielding and additional detector) to 0.59 mg F/g Ca, a factor of 1.12. A new set of phantoms was developed and in this work we show that they improved the minimum detectable limit for fluoride in phantoms irradiated using neutrons produced by 2.15 MeV protons on lithium by a factor of 1.55. We compared the detection limits previously obtained using a summed signal from the nine detectors with the detection limit obtained by acquiring the spectra in anticoincidence mode for reduction of the disturbing signal from chlorine in bone. This was found to improve the ratio of the detection of fluorine to chlorine (an interfering signal) by a factor of 2.8 and the resultant minimum detection limit was found to be reduced by a factor of 1.2. We studied the effects of changing the timing of γ-ray acquisition. Our previously published data used a series of three 10 s acquisitions followed by a 300 s count. Changing the acquisition to a series of six 5 s acquisitions was found to further improve the detection limit by a factor of 1.4. We also present data showing that if the neutron dose is delivered to the phantom in a shorter time period, i.e. the dose rate is increased and irradiation shortened then the detection limit can be reduced by a further factor of 1.35.The overall improvement in detection limit by employing all of these changes was found to be a factor of 3.9. The technique now has an in phantom detection limit of 0.17 mg F/g Ca compared to a previous detection limit of 0.66 mg F/g Ca. The system can now be tested on human volunteers to see if individuals with diagnosed fluorosis can be distinguished from the general Canadian population using this technique.

The half-lives of 90mY and 97Ru

In an attempt to improve the accuracy of neutron activation analysis, gamma-ray spectrometry and least-squares methods developed for other nuclides have been applied to redetermine the decay constants of 90mY and 97Ru. Several irradiated samples of each pure element were counted continually through several half-lives, acquiring up to 100 spectra with good statistics. Photopeaks from each nuclide were evaluated with a region of interest integration routine, and each data point corrected for rate-related losses before fitting to an exponential function by a nonlinear least-squares procedure. The half-lives found are 3.204 ± 0.008 h for 90mY and 2.836 ± 0.014 days for 97Ru, where the uncertainty is an estimate of the 95 % confidence level. Although (by Chi squared criteria) the fits to the decay curves were very good and the uncertainty of the resulting half-lives an order of magnitude smaller than the previously published uncertainty, care is necessary before assigning a best value with a totally defensible uncertainty to the overall data set.

129I levels in soils from Ukraine and Slovenia in the last decade

129I is important as an environmental tracer of the biogeochemical cycling of iodine and of the dissemination of nuclear pollution, because anthropogenic 129I has been released from only few point sources and with its short mixing time its distribution therefore reveals the movement of 129I in the environment. A radiochemical neutron activation analysis method was developed to measure the concentration of 129I in soil samples. A procedure to pre-concentrate iodine from up to 150 g of soil was developed and validated using IAEA standard reference material IAEA-375 (Chernobyl soil). The method was applied to determine 129I/127I isotopic ratios as well as 129I and 127I concentrations in soils from several locations in Ukraine collected in 2006, 1996, 1993 and 1989, and from Slovenia, collected at various places in 2009 and 2006. The 127I concentrations in surface soils from Ukraine were in the range 2.3–23.1 µg g−1 and for 129I (11.1–245.7) · 10−8 µg g−1 dry matter with the highest value of 1.47 · 10−3 µg g−1 found in a soil sample collected in Yaniv, Ukraine in July 1993. In soil samples from Slovenia 127I concentrations ranged 0.73–130 µg g−1 and 129I (8.0–245.7) · 10−8 µg g−1. The 129I/127I isotopic ratios of surface soils from Ukraine were in the range of the order of 10−9–10−5 and of 10−10–10−8 for soils from Slovenia. The highest isotopic ratio 13.6 · 10−5 was found in a soil sample collected in Yaniv, Ukraine in July 1993.

Determination of trace concentrations of thorium in uranium oxide matrix by epithermal instrumental neutron activation analysis

An epithermal instrumental neutron activation analysis (EINAA) method using cadmium filter was standardized to determine trace concentrations of thorium in four samples of uranium oxide (U3O8) samples. Samples and thorium standards, wrapped with cadmium foil, were irradiated at a reactor neutron flux of about 1012 cm−2 s−1. Radioactive assay was carried out using a Compton suppressed anticoincidence gamma ray spectrometer consisting of HPGe-BGO detectors coupled to MCA. Concentrations of thorium in these samples were found to be in the range of 15–72 mg kg−1. EINAA results were validated by determining thorium concentrations in uranium matrix by standard addition method. EINAA results were compared with those obtained by two wet chemical methods namely ion chromatography (IC) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results obtained by the three methods were found to be in good agreement, indicating further validity of the proposed EINAA method.

Determination of arsenic in food and dietary supplement standard reference materials by neutron activation analysis

Arsenic was measured in food and dietary supplement standard reference materials by neutron activation analysis for the purpose of assigning certified or reference As mass fractions and to assess material homogeneity. Instrumental neutron activation analysis was used to value assign As in candidate SRM 3532 Calcium Dietary Supplement and candidate SRM 3262 Hypericum perforatum (St. John’s Wort) Aerial Parts down to about 100 μg/kg. Values were also determined for two additional candidate St. John’s Wort SRMs with As mass fractions <100 μg/kg. The presence of significant amounts of 24Na and 82Br limited the reproducibility of the method below 100 μg/kg. For measurement of lower As mass fractions, a radiochemical neutron activation analysis method with extraction of As3+ into diethyl-dithiocarbamate in chloroform and detection limits down to 0.1 μg/kg. As was used to value-assign As mass fractions for SRM 3280 Multivitamin/Multielement Tablets and for candidate SRM 3233 Fortified Breakfast Cereal, and at <10 μg/kg in candidate SRM 1845a Whole Egg Powder.

Arsenic Content in Inactive Tissue: Human Hair and Nail

Nuclear reactor based Neutron Activation Analysis (NAA) method was applied for the determination of arsenic content in human scalp hair, nail and water samples at the south western part of Bangladesh.Average Arsenic (As) content in male and female hair samples were 0.93 �og/g and 3.71 �og/g respectively and also As content in nail samples

Selenium content of Argentinean infant formulae and baby foods by pseudo-cyclic instrumental neutron activation analysis coupled to Compton suppression

The selenium levels of Argentinean infant formulae and baby food were measured using the 162-keV gamma-ray of 77mSe (t ½ = 17.4 s) by a pseudo-cyclic instrumental neutron activation analysis (PC-INAA) method in conjunction with Compton suppression spectrometry (CSS). For comparison purposes, 5 selected infant formulae were also analyzed for selenium by a radiochemical neutron activation analysis (RNAA) method. The selenium levels for three samples agreed between ±2.8 and 6.5 % while the other two differed by 12 and 17 % which could perhaps be attributed to sample inhomogeneity. The selenium content of cow milk-based infant formulae varied from 42–146 μg kg−1 compared to 52–63 μg kg−1 for soy-based milk formulae. In the case of baby foods, the selenium levels varied from 34 to 74 μg kg−1. The detection limits for selenium by PC-INAA–CSS for all the samples analyzed in this work were between 8.5 and 65 μg kg−1 depending on the major elements present in the samples, while it was 20 μg kg−1 for the RNAA method. The expanded uncertainty (κ = 2) of the PC-INAA–CSS method was 7.0 % at the end of cycle #4 for a sample containing 73.7 μg kg−1 selenium compared to the RNAA value of 24.2 % for a sample of 67.0 μg kg−1 selenium content.

Rapid determination of silver in cultivated Japanese and South Korean oysters and Japanese rock oysters using the 24.6-s neutron activation product 110Ag and estimation of its average daily intake

Soft tissues of cultivated Japanese (Miyagi Prefecture) and South Korean (Koje-do and Kosong) oysters and Japanese rock oysters (Honshu Island) were analyzed to measure silver levels. The soft tissues, namely hepatopancreas, gill, muscle, and mantle were separated, freeze-dried, pulverized, and analyzed by an instrumental neutron activation analysis method in conjunction with compton suppression spectrometry (INAA-CSS). The method consisted of the irradiation of samples in a neutron flux of 5 × 1011 cm−2 s−1 using the rapid transfer system in an inner pneumatic irradiation site of the Dalhousie University SLOWPOKE-2 reactor (DUSR) facility for 12–15 s, decay for 20 s, and counting for 60 s. The 657.8-keV gamma-ray of the 24.6-s nuclide 110Ag was used for assaying silver. The method was validated using NIST, NRC and NIES certified reference materials. An absolute detection limit of 0.05 μg silver using NIST SRM 1566b Oyster Tissue was achieved. About 10–50 times higher levels of silver were found in cultivated Japanese oysters compared to the South Korean ones. The silver concentrations in cultivated oysters in Miyagi Prefecture showed the following trend: gill > mantle > hepatopancreas > muscle as well as on the age. Rock oysters generally had higher silver content compared to cultivated oysters. A very preliminary value of about 0.466 μg silver average intake per person per day was estimated from the consumption of oysters by the people living in the Sendai city of Miyagi Prefecture.

Epithermal instrumental neutron activation analysis in conjunction with anti-coincidence gamma-ray spectrometry for investigating iodine levels in Canadian foods

In order to reduce interferences from high activities of 24Na, 56Mn, 82Br, and 38Cl as well as to improve detection limits, precision, and accuracy of measuring iodine levels in biological materials, foods and diets in particular, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence (EINAA-AC) gamma-ray spectrometry was employed. The Compton scattering background in the region of the 442.9-keV photopeak of 128I was significantly suppressed by anti-coincidence counting. In order to validate the EINAA-AC method as well as to evaluate its broad applicability to diverse types of biological material, 17 NIST and IAEA reference materials containing very low to high levels of iodine as well as interfering elements were analyzed by the EINAA-AC method. The samples were irradiated in the cadmium-lined pneumatic site at a neutron flux of 2 × 1011 cm−2 s−1 of the Dalhousie University SLOWPOKE-2 Reactor (DUSR) facility for 10 or 20 min followed by 1-min decay and 30-min counting. The detection limit for iodine by EINAA-AC was improved by a factor of 2–5 compared to EINAA depending on the sample matrix and other factors, and a limit of 3–5 μg kg−1 was achieved for low-salt foods. We found the RSD to be about ±5 % above 200, increasing to ±10 % at 20, and then to greater than ±30 % at about 5 μg kg−1 iodine levels.

Reversed-phase extraction chromatography–neutron activation analysis (RPEC–NAA) for copper in natural waters using Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol

A preconcentration neutron activation analysis method has been developed for the determination of trace levels of Cu in natural waters including seawater with an absolute detection limit of 0.106 μg. The method involves the preconcentration of Cu onto Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol using reversed-phase extraction chromatography (RPEC). Copper is assayed through its neutron activation product 66Cu (half-life = 5.10 min) by direct irradiation of the resin bed. Factors affecting the uptake of Cu onto the ligand-impregnated resin have been investigated; these include flow rate, pH, column height, presence of other trace elements, major elements, and interfering matrix. The RPEC–NAA method has been validated by analyzing NIST and NRC water reference materials.

Determination of the Elemental Composition of Coffee Using Instrumental Methods

Although the content of elements in coffee is only about 5 % (m/m), it seems to be a good indicator of the coffee authenticity. Apparently, it can bring the useful information about individual elemental patterns that are distinctive to the origin of growing soils for coffee plants in addition to cultivation and environmental conditions used. The elemental analysis of coffee by means of instrumental measurement methods may have other uses. It can be used to prove the high quality and safety of raw coffee beans, various coffee byproducts, and the final coffee product in the market. Commonly, different atomic absorption and emission spectrometry and instrumental neutron activation analysis methods are used to determine concentrations of various elements in green, roasted, and ground or instant coffees and coffee infusions, but these samples have to be suitably prepared prior to the analysis.

Determining the amount of Br, Na and K in six wheat samples with neutron activation analysis (NAA) method in Arak, I.R. Iran

Accurate knowledge of the trace elemental concentrations in wheat and its products is of great importance from a nutritional point of view. In this study, six wheat samples were prepared from the agriculture research center of Arak named Sardari, Amir, MV-17, Batava, Karaj-2 and Alvand; they were analyzed by neutron activation method (NAA). In this method, Isfahan miniature reactor as a neutron source and relative NAA method has been used as the analysis type. In this design in order to record gamma spectrum the MCA system and high purity germanium detector were used. Finally, the concentration of the trace elements such as Br, K and Na value was determined for the Sardari, Amir, Alvand, MV-17, Batava, Karaj-2 wheat samples. The average concentration of trace elements in all wheat samples in the studied area are 2.41(0.8597−6.1175) mg kg−1 for Br, 13.42(8.7063−24.696) mg kg−1 for Na and 463.30(434.22−505.45) mg kg−1 for K, respectively. These were compared with other reports results. This study has been conducted as the first time for this region.

Determination of concentration of iodine in grass and cow milk by NAA methods using reactor neutrons

Instrumental and preconcentration methods of neutron activation analysis (NAA) have been standardized for the determination of concentration of iodine in grass and cow milk samples, respectively. To study the transfer of iodine from grass to milk, known quantity of grass spiked with potassium iodide solution was fed to a cow. The spiked grass samples and milk samples, obtained from the cow after the ingestion of spiked grass, were collected. Iodine was separated from the milk samples chemically using Dowex 1X8 anion exchange resin. Spiked grass and ion exchange resin samples were neutron irradiated and radioactive assay was carried out using a 45 % relative efficiency HPGe detector coupled to an 8k channel analyzer. Iodine concentrations in spiked grass samples were found to be in the range of 1,487–2,002 mg kg−1. Concentration of iodine in milk after 12 h of feeding the cow with spiked grass was 871 ± 56 μg L−1 which was reduced to 334 ± 32 μg L−1 after 48 h.

Estimation of total as well as bioaccessible levels and average daily dietary intake of iodine from Japanese edible seaweeds by epithermal neutron activation analysis

An epi-thermal instrumental neutron activation analysis (EINAA) method in conjunction with Compton suppression spectrometry (EINAA-CSS) was used for the determination of total iodine in eight different species of edible seaweeds from Japan. This method gave an absolute detection limit of about 2 μg. The accuracy of the method was evaluated using various reference materials and found to be generally in agreement within ±6% of the certified values. The longitudinal distributions of iodine at different growing stages in Japanese sea mustard and tangle seaweeds were investigated. For a 150-cm-high tangle, the highest concentration (5,360 mg/kg) of iodine was found at the root, then decreased slowly to 780 mg/kg in the middle portion (60–75 cm), and increased to 2,300 mg/kg at the apex. On the other hand, for a 190-cm-high sea mustard the highest levels of iodine were found both at the roots (164 mg/kg) and apex (152 mg/kg) with lower values (98 mg/kg) in the middle section. In order to estimate the bioaccessible fraction of iodine, seaweeds were digested by an in vitro enzymolysis method, dietary fibre separated from residue, and both fractions analyzed by EINAA-CSS. The average daily dietary intakes of total (0.14 mg) as well as bioaccessible fraction (0.12 mg) of iodine from the consumption of sea mustards were estimated.