Neutron Activation Analysis Method Research Articles

Instrumental activation analysis of agricultural soils in maharashtra state (India) by a 252Cf neutron source

The agricultural soils from different regions in Maharashtra State were subjected to thermal neutron irradiation in a 252Cf spontaneous fission neutron source at an integrated flux of ∼10 9ns −1. The activities of the radioisotopes formed, viz. 24Na, 28Al, 42K and 56Mn, were measured on a multichannel analyzer coupled to a high purity germanium detector, and the content of these elements in soils was estimated by comparator method of instrumental neutron activation analysis.

Investigations of the separation of Np, Pa, U, Th and ree in geological samples

In the first part some methods of the radiochemical neutron activation analysis of U, Th and REE trace amounts in geological samples have been studied. They are: (i) cation exchange and extraction, and (ii) extraction chromatography. The behaviour of U and Th was also observed and conclusions were made regarding the applicability of the methods for the rocks which are rich in U and Th but depleted of REE. The method is recommen ded for the selective separation of U and Th. The second part represents an effective separation method for the determination of all REE and Th contents in monazites.

Variation in the elemental composition of municipal refuse incinerator ashes with time of sampling

Due to the ever increasing quantities of solid waste, more refuse incinerators are coming on line in the United States. Toxic metals and organics in the resulting ash to be disposed and in suspended particulates that escape the stack are major deterrents to refuse incineration. Since refuse composition is highly variable with time, it was of interest to determine the extent of variation in element composition of the resulting fly ash and bottom ash with time of sampling. In the present study, the ashes were sampled at monthly intervals from the same refuse incinerator and analyzed for 38 elements using neutron activation analysis, emission spectrometry and other methods. Possible factors including refuse composition and reactions occurring during refuse incineration as they affect the elemental composition of refuse ashes are discussed.

Simultaneous determination of iodine and selenium in biological samples by radiochemical neutron activation analysis

Regarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides 128I and 75Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed.

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 uranium, thorium, and 18 other elements in high-purity molybdenum by radiochemical neutron activation analysis

A radiochemical neutron activation analysis method for the determination of 22 elements in high-purity tungsten has been developed. For the assay of indicator radionuclides with long half-lives, the radiochemical separation was performed from HF/H2O2, HF/NH4F and HCl/H2SO4 media by a combination of cation and anion exchange on a Dowex 50 W × 8 and Dowex 1 × 8 column. An effective removal of the matrix-produced radionuclides of W and Re was achieved. U was determined via 140La, the daughter nuclide of the fission product 140Ba. Limits of detection of 2 ng/g for U and 0.02 ng/g for Th can be achieved. For the other elements, the limits of detection are between 0.004 ng/g (Sc) and 200 ng/g (Sr). The elements Hf, Ta and Sb could be determined by instrumental neutron activation analysis. This method was applied to the analysis of two tungsten powder samples of different purity grade. The results and limits of detection are compared with those of other methods.

Combination of neutron activation analysis, tracer techniques, and biochemical methods in the investigation of selenium metabolism

In several studies on rats, the metabolism of selenium was investigated. The quantitative determination of the element was carried out by instrumental neutron activation analysis. For in vivo tracer experiments, 75Se-labeled selenium compounds were used. In addition to these methods, procedures for the measurement of the selenoenzyme glutathione peroxidase, and for the investigation of other selenoproteins, were applied. In this way, information on the specific pools and sites of action of the element, on biologically important selenoproteins and the regulation of the selenium metabolism, was obtained.

Vanadium determination at the ultra-trace level in biological reference materials and serum by radiochemical neutron activation analysis

In order to help resolve present inconsistencies of two orders of magnitude or more in reported levels of vanadium in human serum and blood, a totally postirradiation radiochemical neutron activation analysis (NAA) method was further developed and applied to some pertinent nanogram and subnanogram reference materials. In particular, the second generation human serum reference material of Versieck was found to contain a value of 0.67 +/- 0.05 ng/g dry wt., corresponding to 0.061 +/- 0.005 /4/ ng/mL original fresh serum. Results are also reported for some other appropriate CRMs. Additionally, a small-scale study in 10 normal subjects (5 m, 5 f) revealed levels similar to those in the serum reference material and in agreement with the lowest data reported in the literature. Discussion of pitfalls of vanadium determination and the use of reference materials is included.

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 Se(IV) in water by neutron activation analysis after coprecipitation of metal dibenzyldithiocarbamate with phenolphthalein

A neutron activation analysis method for the determination of Se(IV) in natural waters is described. It is based on the coprecipitation of the metal dibenzyldithiocarbamate with phenolphthalein. The precipitate is collected on 0.45 μm membrane filters and selenium is determined by instrumental neutron activation. A Se(IV) radiotracer (75Se, T=120 d) was used to establish optimum conditions and to evaluate the chemical yield. Samples of sea and canal water were analyzed.

Sur les traces de l'argent du Potosî

Suivre un métal d'une provenance donnée « à la trace » n'est pas une simple métaphore. Les alliages métalliques (et donc monétaires) contiennent en effet à côté des éléments majeurs (or-argent-cuivre pour les monnaies d'or ; argentcuivre pour les monnaies d'argent) que l'on mesure en pourcentage, des éléments- traces présents en quantités infimes, mesurées en parties pour million ou ppm (10 6 g/g). Ces traces constituent comme la carte d'identité, ou l'empreinte digitale, des minerais sources. Leur détection et leur mesure sont d'avancée récente ; seule l'application de la physique nucléaire au matériel archéologique les a rendues possibles.

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.

Non-destructive determination of aluminum in biological reference samples using neutron activation analysis

The non-destructive methods of thermal and epithermal neutron activation analysis have been employed to determine the aluminum concentration of seven National Institute of Standards and Technology certified biological reference materials. Through the judicious use of both thermal and epithermal neutron activation analysis using bare and boron-lined irradiation carriers, the major and minor contributions of the31P/n, α/28Al and of the28Si/n, p/28Al reactions, respectively, to the27Al/n, γ/28Al reaction could be corrected for explicitly. Based on replicate determinations precision of the analysis ranged from 2.5% for citrus leaves determined at the 75 ppm level to 18% for bovine liver measured at the 1 ppm level. Accuracy was demonstrated whenever possible by comparison to existing published data.

The influence of an additional filter in epithermal neutron activation analysis

Additional filters of tungsten and sodium in different thicknesses have been used in the epithermal neutron activation analysis of geological samples to reduce the interferences caused by resonance neutron capture in these two elements. The results show that a selective reduction of the interfering activities in favor of the activities sought can be obtained. Improvements in terms of detection sensitivity and precision in the γ-spectrometric determinations of Sc, Fe, Co, La, Sm, Eu, Gd, Tb, Yb, Lu, Th and W have been calculated. The possible applications of the filtered epithermal neutron activation analysis (FENA) method to different kinds of samples are also briefly discussed.

Contamination of Platinum Resistance Thermometers at High Temperature Through Their Silica Sheaths

Some high-temperature platinum resistance thermometers were tested at the IMGC to evaluate the performance in different furnaces and environments between 980 °C and 1080 °C. They exhibited a large instability when maintained in close contact with an Inconel-600 environment, suggesting that their silica sheaths might be permeable to metal vapour released by Inconel. Different experiments were carried out to investigate the phenomenon by exposing some pure platinum wires sealed in silica capsules to an Inconel environment at 1080 °C. First, the exposed platinum wires were analysed with the neutron activation analysis method to determine the contamination from the environment; and after, the effects of surrounding gas on the diffusion of metal vapours through the silica sheaths were examined by means of radiotracers from an activated Inconel source. All the experiments demonstrated that at high temperature the silica sheaths are permeable to metal vapours, thus the platinum resistance thermometers can be easily contaminated by a metal environment.

実験的家兎動脈硬化症における中枢神経組織内カルシウム, 燐, マンガン, マグネシウム沈着とelastaseの金属沈着予防作用について

The aims of this study were shed light on the evaluation of calcium (Ca), phosphorus (P), manganese (Mn), and magnesium (Mg) in central nervous system (CNS), liver, and kidney of rabbits with atherosclerosis experimentally induced by a cholesterol-rich diet. We also investigated the protective effect of exogenous elastase on deposition of these metals in the CNS and soft tissues.Twenty five male rabbits, weighing 2, 000g, were divided into equal six groups. The experimental atherosclerosis was performed by the modified procedure of Kritchevsky et al. Group A was fed a standard diet for three months. Also for three months, Group B was fed a standard diet that was 1.5% cholesterol-rich, and Group C had a 1.5% cholesterol-rich diet plus daily intraperitoneal administrations of elastase 450EL.U/kg. Other groups were fed a standard diet (Group D), a 0.67 cholesterol-rich diet (Group E) and a 0.67% cholesterol-rich diet plus daily intraperitoneal administration of elastase 450 EL.U/Kg (Group F) for six months. After feeding rabbits with the above regimens for three to six months, the rabbits fed with cholesterol-rich diet (Groups B, C, E and F) were shown to have atherosclerosis using biochemical and histological techniques. The amelioration of atherosclerotic lesion in each tissue induced by the cholesterol-rich diets was confirmed with intraperitoneal administration of elastase.Ca, P, and Mn contents in the frontal lobe, pons, cerebellum, spinal cord, liver, and kidney of each rabbit were determined by the well-established neutron activation analysis method, and the Mg content was obtained by inductively coupled plasma emission spectrometry. Deposits of Ca, P, Mn, and Mg in the CNS were remarkable in rabbits fed with cholesterol-rich diets for 6 months compared to those in rabbits fed with 1.5% cholesterol-rich diets for 3 months, metal deposition in CNS being dependent on the length of the cholesterol feeding period. In rabbits with a 0.67% cholesterol-rich diet, the level of Ca, P, Mn, and Mg in CNS tended to decrease, and in part, significantly reduced by administration of exogenous elastase. It appears likely that rabbits with atherosclerosis have higher concentrations of Ca, P, Mn, and Mg in their CNSs, and that these metals are removed from the CNS by the action of elastase.

Dopant-polymer interaction: MoCl 5-doped polyacetylene

Polyacetylene is doped with MoCl 5. The doping levels determined using the method of neutron activation analysis indicate that the atom ratio [Cl]/[Mo] varies from 5 to 1.6, depending on doping time. The C 1s XPS (X-ray photoelectron spectroscopy) binding energy (BE) decreases from 283.7 eV for the pristine PA to 282.9 eV, similar to that of WCl 6-doped PA as reported in our previous work, but opposite to that of I 2- and AsF 5-doped PA. The lowering of the BE means that the outer shell electron densities of carbon increase after the doping. The Cl 2p XPS of the doped PA shows that there is only one type of chlorine in the adducts. Mo 3d XPS shows that there are two states of Mo existing in the doped PA, being state A (MoCl 2(CC) 4) and state B (Mo(CC) n ), quite different from those in the WCl 6-doped PA. The level created at 1.72 eV related to state B is closer to the HOMO π orbital (BE 1.8 eV) of the pristine PA, and is therefore a more shallow level than the state created at 1.24 eV (due to state A Mo). Several olefins from more than one PA chain can interact with one Mo atom, allowing electron transfer from one PA chain to another.

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.

Multielement ultratrace analysis of molybdenum with high performance secondary ion mass spectrometry

Electron beam melting has been used to obtain ultrapure refractory metals that are gaining importance in metal oxide semiconductor-very large scale integration (MOS-VLSI) processing technology, fusion reactor technology, or as superconducting materials. Although the technology of electron beam melting is well established in the field of production of very clean refractory metals, little is known about the limitations of the method because the impurity level of the final products is frequently below the detection power of common methods for trace analysis. Characterization of these materials can be accomplished primarily by in situ methods like neutron activation analysis and mass spectrometric methods [glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS)]. A suitable method for quantitative multielement ultratrace bulk analysis of molybdenum with SIMS has been developed. Detection limits of the analyzed elements from 10−7g/gdown to 10−12g/g have been found. Additional information about the distribution of the trace elements has been accumulated.

Untersuchungen an syenitoiden und gabbroiden Gesteinen mittels Mößbauer-Spektroskopie und Neutronenaktivierungsanalyse

The study of trace element distribution in minerals from basic and intermediate igneous rocks is actually important, esp. in connection with tectonic and magmatic processes. We can find some information about metallogenetic aspects by means of combination of 57Fe Moessbauer spectrometric investigation and trace clement geochemistry, esp. the method of instrumental neutron activation analysis.