Neutron activation analysis of uranium via239Np

A method is described for the analysis of uranium by neutron activation. The sample is brought into solution and the neptunium present is reduced to oxidation state (IV); quantitative extraction of²³⁹Np in the acidified aqueous phase (0.4<pH<1) is performed with a solution of HTTA (0.2M) in benzene. The use of a low-power reactor (100 kW_thermal) enables determination of uranium at a lower concentration limit of 33 ng for periods of irradiation. cooling and measurement of 3 hours, 24 hours and 900 seconds, respectively.     

Neutron activation analysis of very pure silicon wafers

Procedure and results of instrumental neutron activation analysis of very pure silicon wafers of 12.5 and 15 cm diameter are described. It is shown that the determined contaminations are mainly present on the surface or in a surface layer of the wafers. With the method outlined here very low limits of detection for a large number of elements are obtained. The analyses also confirmed that two routine process cleaning procedures do not contaminate the surface of the waters.     

Neutron activation analysis of trace elements in cataracts

The knowledge of the role of trace elements is a necessary condition for the investigation of cataract etiopathogenesis. The deposition of trace elements in eye lens may be influenced by many vital factors and, therefore, the effect of sex, age and locality on the content of these elements was investigated. The determinations of elements were carried out by instrumental neutron activation analysis, and the results were evaluated with the aid of statistical tests. The effect of locality being taken as a set of local ecological factors has been proved as a dominant factor.     

Neutron activation analysis of rare earth impurities in metallic uranium

A method with a sensitivity of 2·10⁻⁷ to 1·10⁻¹⁰% has been developed for determining Yb, Ho, Dy, Gd, Eu, Sm and La impurities in metallic uranium by means of neutron activation. The method is based on a preliminary chromatographic separation of the total amount of rare earth elements from uranium by passing the solution in sulphuric acid through KU-2 cation exchange resin and eluting the traces of uranium retained by the resin with a solution of ascorbic acid. The rare earth impurities are then eluted from the resin with 4–5N HCl, evaporated, and irradiated for 20 hours with a neutron flux of 1.2·10¹³ n·cm⁻²·sec⁻¹. Subsequently the traces of the rare earth elements are co-precipitated with Fe(OH)₃, dissolved in concentrated HCl and separated from the iron and other impurities by passing the solution through Dowex 1X8 anion exchange resin in the chloride form. The individual rare earth elements are then separated from each other using KU-2 cation exchange resin and a solution of ammonium α-hydroxyisobutyrate as the eluant.     

Neutron activation analysis for trace elements in foods

Food samples reflecting average food consumption by an adult in the southeastern, northeastern, central, and western parts of the United States were collected and prepared as if for consumption. The prepared foods were divided into twelve different food categories and analyzed by instrumental neutron activation analysis. The concentration of Ca, Mn, Mg, Al, Na, K, Cu, Cl, Sb, Hg, Se, Fe, Zn and Co is reported for these food samples.     

Preconcentration and neutron activation analysis of thorium and uranium in natural waters

Uranium and thorium were analyzed in commercial bottled waters and in fresh waters, such as tap water, by neutron activation analysis. The analysis was applied after a preconcentration step from a batch of 1–3 dm³ water under investigation. The adsorption was performed in the presence of a small amount (about 1 g) of an adsorber derived from the salt of a-hydroxyquinoline and benzilic (diphenylglycolic) acid, adsorbed onto charcoal. The preconcentration method has shown to be rapid and reliable. The overall method was set in order to have an alternative method of comparison with other different methods of analysis. The proposed method may be applied to different fresh water samples. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preconcentration of trace elements for neutron activation analysis using activable tracers

Use of an enriched isotope as an activable tracer is proposed for the preconcentration of trace elements in neutron activation analysis. As a test of this method, contents of cadmium in various biological standard samples were determined by addition of an enriched¹¹⁶Cd tracer in the preconcentration step followed by neutron irradiation and -ray spectrometry. The principle, advantage, and limitations of the method are also discussed.     

Neutron activation analysis in forensic investigations: Trace elements characterization of cigarettes

A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO₂-P, was prepared by impregnating a crown ether derivative, 4,4￠,(5￠)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO₂-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO₃ This revised version was published online in July 2006 with corrections to the Cover Date.     

Neutron activation analysis of trace elements in Japanese hormesis cosmetics

In Japan, cosmetics claiming hormesis effect are available through Internet. Although these cosmetics show the contents, they never mention the minor elements and radioactive sources. The existence of radioisotopes, however, was observed by measurements of the gamma-rays with a HPGe detector. In this study, in order to clarify the contents of trace elements, the hormesis cosmetics including radioactive sources were analyzed using INAA, PGAA and NAA with multiple gamma-ray detection (NAAMG). Nineteen elements were analyzed quantitatively in hormesis cosmetics by INAA, PGAA and NAAMG and 16 elements were detected qualitatively by SEM-EPMA.     

Preconcentration and instrumental neutron activation analysis of acid rain for trace elements

A combination of instrumental and preconcentration neutron activation analysis (NAA) methods has been developed for multielement determination in acid rain. Concentrations of 24 elements have been measured in the particulate matter of rainwater by the instrumental NAA method which involves 3 irradiation and 4 counting periods. Trace elements in the soluble fraction of rainwater have been preconcentrated using Chelex-100 resin. Various factors that could influence the retention of elements on to the resin have been examined, and reagent and other blanks investigated in detail. Concentrations of 15 elements have been measured by directly irradiating the resins. A graphite furnace atomic absorption spectrometry method has been used for determining Cd and Pb levels in the soluble fraction. Precision and accuracy of the methods have been evaluated, and limits of detection and determination calculated. The methods have been applied to rainwater samples collected from 36 locations across Canada. Enrichment factors, interelement and inter-ion concentration correlation coefficients are discussed     

Neutron activation analysis of selenium and 17 elements in sediment.

Instrumental neutron activation analysis was performed to determine Na, Mg, Al, Cl, Sc, V, Cr, Mn, Fe, Co, Ni, Rb, Sb, Cs, Ba, Ce and Eu in the Pacific core sediment. Selenium was also determined by neutron activation analysis, by applying a solvent extraction method with 2,3-diaminonaphthalene (DAN) as a post-irradiation procedure, after the wet-ashing of the sediment. Homogeneity of trace constituents in the sediment and neutron flux corrections for accurate determination were also investigated.     

Neutron activation analysis of major and trace elements in crude petroleum

We have determined the concentration of 25 trace elements in crude petroleum from seven Libyan oil fields by instrumental neutron activation analysis. Crude oil samples were irradiated with a thermal neutron dose rate of 10¹² and 10¹³ n·cm^–2·s^–1 in the Tajoura research reactor. The concentration of U, Br, Mg, Cu, Na, V, Cl, Al, Mn and Ca is in a range of 0.015 to 84 ppm and that of sulphur of 0.12 to 1.8%. The elements Sc, Cr, Ni, Fe, Co, Zn, Ag, Se, Sb, Ba, Cs, Yb, Hf and Hg have a concentration range of 0.009 to 8747 ppb. The coefficients of variation are within 10%. The elements V and Ni occur as both porphyrin and non-porphyrin and the ratio of these two forms varies over a wide range. The V/Ni ratios are located between 0.17 and 6.67, which are comparable to the reported values for the crude oils from other countries.     

Neutron activation analysis for determination of cerium trace impurity in high purity lanthanum oxide

Cerium trace impurity in high purity lanthanum oxide (99.99%) has been determined by NAA after pre-separation of La matrix. In this method, the sample was dissolved in conc. nitric acid and diluted with water. The final concentration of solution is about 0.1M of nitric acid. It was passed through a MnO₂ column. Under these conditions cerium is retained on the column quantitatively without retaining lathanum. Cerium is eluted with 4M nitric acid. The recoveries of Ce were checked with tracers and by standard addition to lanthanum oxide matrices. Results obtained on a high purity lanthanum oxide are reported here.     

Neutron activation analysis for bulk and trace elements in urine.

Problems in sampling urine for trace element analysis by neutron activation are systematically examined. Collection, storage, sample preparation and contamination hazards during irradiation are studied in detail. Three different sizes of urine samples are prepared for analysis, depending on the concentration and nuclear properties of the elements, and suitable multielement doped urine standards are used. As, Br, Ca, Cl, Co, Cr, Cs, Cu, Hg, I, K, Mg, Mn, Na, Rb, Sc and Zn are determined. The extreme care given to sample collection, use of “ultra-clean” vials, and work in a dust-free room, allows consistent values to be obtained over long periods of time. A literature review of the amounts of forty elements present in urine per day is also given.     

Neutron activation analysis of 13 minor and trace elements in geological samples

A scheme of analysis for the determination of Na, Mn, U, Th, Hf, Sc, La, Ce, Eu, Tb, Co, Rb and Cs in geological samples using the neutron activation technique has been described. The results obtained in this work on eight geological standard rocks and a trachyte are presented and compared with literature data.     

X射线荧光法测定纯铝制品中的杂质元素

本文主要介绍铝粒、铝线、铝块等纯铝制品中主要杂质元素的X射线荧光测定法。利用光谱标准物质,优化分析条件,建立纯铝制品中各杂质元素的分析曲线, 此方法精密度好,准确度高,操作简便、快速,能够适应生产快速检验的需要。     

锆存在时铀中杂质元素的化学分离-ICP-AES法

采用磷酸三丁酯（TBP）－氢化煤油萃取油、过氧化氢掩蔽钛、磷酸氢二铵沉淀锆的方法，用ICP－AES法同时测定了锆存在在时铀中的铁、锰、铜、硅、铝、镍和钛7种杂质元素的含量。当测定范围在100μg/g-1000μg/g时，相对标准偏差＜9．0％，回收率为96％－109％。     

Neutron activation analysis of uranium in human bone,drinking water and daily diet

Uranium in human bone, drinking water and daily diet has been determined by neutron activation analysis using the²³⁸U(n, γ)²³⁹U reaction. An improved scheme for the separation of the²³⁹U is proposed; with this scheme, after neutron irradiation in a 100 kW TRIGA reactor, a uranium content as low as 5·10⁻¹¹ g can be determined reliably, rapidly and easily. A wide range of uranium concentrations, from about 0.1 ppb up to about 10 ppb has been found in the bones of normal Japanese. Water from several Japanese city water services, and the daily diet taken in two Japanese cities, have been found to contain an average 9·10⁻⁹ g/l and 1.5 μg per person-day uranium, respectively.     

Neutron activation analysis for 39 elements in small or precious geologic samples

A procedure has been developed for the determination of 39 elements in a single sample of rock or mineral by neutron activation analysis. After the sample has been irradiated with neutrons, it is separated chemically into 12 groups for radioassay with one NaI(Tl) and two Ge(Li) detectors. Three chemists can complete the separations and sample preparations within 7 hrs after the end of the neutron irradiation. Carrier is added and a chemical yield is determined for each element. About two months are required to obtain complete data for a particular sample, but several samples can be analyzed concurrently. In a sample of typical igneous material weighing 0.5 g, half of the elements can be determined to better than ±5 per cent precision and accuracy, and fewer than a fifth with precision and accuracy poorer than ±25 per cent.