Multielement analysis of Chinese Environmental Reference Materials by instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) has been applied for the simultaneous determination of up to 33 elements including major, minor and trace elements in the environmental reference materials soil and coal fly ash from China. The procedure involves both short and long irradiations followed by the measurement of the gamma spectra with a Ge(Li) detector. The analytical results are presented and discussed.     

Determination of trace elements in biological standard kale by neutron activation analysis

Fifteen elements at trace levels have been determined by neutron activation analysis in the biological standard kale distributed byBowen. La, Br, As, Se, Sc, Ag, Zn, Co, Cr, Sb, Eu, Fe, and Zr have been determined by a nondestructive technique using a high-resolution Ge(Li) detector. Two more elements, Au and Hg, have been determined after radiochemical separation. The nondestructive procedure is shown to yield data in generally good agreement with those obtained by destructive techniques. Potential sources of error in the nondestructive technique are discussed.     

Multi-element standard for routine instrumental activation analysis of trace elements in rocks and tectites

The use of high-resolution Ge(Li) detectors in non-destructive instrumental neutron activation analysis (INAA) of mineral materials makes possible the simultaneous determination of a number of trace elements. In routine applications of INAA the use of a multi-element standard (MES) has proved to have advantages over a set of standards for each determined element. An MES has been prepared containing 8 trace elements mixed in a suitable proportion and giving, after neutron activation, long-lived γ-emitters, the γ-ray lines of which regularly occur in the γ-ray spectra of silicate mineral materials. This method has been used in the determination of Sc, Cr, Co, Rb. Cs, Eu, Hf and Th in samples of standard rocks and moldavites.     

The influence of seasonal changes in the concentration of trace elements in liver tissue of various wild animals determined by instrumental neutron activation analysis

Levels of some of the most essential minerals in liver tissue of wild animals living in game reserves in South Africa were studied by instrumental thermal neutron activation analysis and a Ge(Li) detector. In addition, some of the most important trace elements were determined by atomic absorption spectrometry. The distribution of the content of the various elements was followed for about two years and attempts have been made to explain the influence of seasonal fluctuations of the micronutrients determined.     

Instrumental neutron activation analysis of Obsidian rock

An instrumental neutron activation analysis technique has been developed for the simultaneous determination of up to 30 elements including major, minor and trace elements in Obsidian Rock (a proposed NBS-SRM-278). INAA method involves both short and long irradiations followed by gamma-ray activity measurement with a Ge(Li) detector. The accuracy of the procedure has been checked by analyzing IAEA Reference Materials.     

Instrumental neutron activation analysis of fly ashes and emissions

Instrumental neutron activation analysis (INAA) has been utilized for the analysis of 19 different fly ashes, 1 sample of coal and 3 samples of industrial emissions. Both short and long irradiations in a nuclear reactor have been used. The irradiated samples have been measured by means of a computer-based Ge(Li) gamma-ray spectrometer. The concentrations of 27 elements have been determined in the samples.     

Neutron activation analysis of an iranian cigarette and its smoke

Non-destructive neutron activation analysis, employing a high-resolution Ge(Li) detector, was applied to determine the concentration of 24 trace elements in the tobacco of the Zarrin cigarette which is commercially made in Iran. These elements are: Na, K, Sc, Cr, Mn, Fe, Co, Zn, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Eu, Tb, Hf, Au, Hg and Th. The smokes from the combustion of this tobacco and of the cigarette paper were also analysed for these elements and the percentage transference values were calculated.     

Determination of rare-earth elements in rock samples by neutron activation analysis with a lithium-drifted germanium detector after chemical group-separation

A lithium-drifted germanium detector combined with chemical group-separation has been utilized for the determination of rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Tm, Yb and Lu) in rock samples by neutron activation. This procedure has the advantage of a low background level which cannot be attained in the non-destructive method. The combination of the Ge(Li) detector and chemical group-separation also offers a distinct simplification in the correction of contributions from other nuclides. For optimum utility of a Ge(Li) detector in neutron activation analysis, chemical group-separations are recommended.     

The determination of zonally distributed impurities in diamond by instrumental neutron activation analysis

A technique is described for the determination by instrumental neutron activation analysis of the zonal distribution of trace elements in diamond. Individual diamonds were irradiated and then dissolved in stages into 10 to 20 fractions in molten sodium nitrate. The activity of the material dissolved in each fraction was measured using a well-shielded Ge(Li) detector. Because of the small sample sizes involved, many elements typically found in diamond were below the limits of detection even though the experimental conditions were optimised for high sensitivity. The data obtained for a clear, a green and a coated diamond are given here to show the scope of the method. High levels of some elements in the outermost layers of all the diamonds are thought to have been due the implantation of surface contaminants during neutron irradiation. Removal of the outer few microns of irradiated diamonds before counting will avoid this source of error.     

Instrumentelle Aktivierungsanalyse an Lunarem Material

Lunar soil samples of the Luna 16 Luna 20 missions were analysed by neutron activation in a neutron generator and a nuclear reactor, respectively, and following gammaspectrometry by NaI(T1) and Ge(Li) detectors. By 14 MeV neutron activation there were determined the abundances of 5 major elements (O, Mg, Al, Si, Fe) and by reactor activation the abundances of 18 major and trace elements (Na, K, Sc, Cr, Mn, Fe, Co, Mo, La, Ce, Sm, Eu, Tb, Yb, Lu, Hf, W, Th) and the detection limits of 4 additional elements (As, Rb, Sb, Cs). The standard rocks BM and GM of the ZGI were used as standards in the reactor activation analysis.     

New Developments in Activation Analysis for Material and Environmental Sciences

Activation analysis in general and mainly reactor neutron activation analysis (NAA) has been used extensively for measuring trace elements in high purity materials, particularly semiconductor materials. The advantages of NAA in determination of trace elements differ from one semiconductor material to another. For all of them the inherent properties of activation analysis especially those of non contamination with the reagents, low blanks and high sensitivity are the reasons for the choice of NAA as the main analytical procedure. These inherent properties are essential for analysis of high-purity materials where concentrations of ppb's and sub ppb's have to be measured. NAA is specially suitable for the determination of trace elements in silicon due to the very short lived very low activity induced by neutron reaction in silicon. This enables easy instrumental (i.e. without chemical separations) determination of trace elements in silicon. In the HFR reactor at Peten, Netherlands, a special facility was constructed for irradiation of silicon samples of Philips, in which silicon wafers of up to 15 cm diameter can be irradiated with 4 × 10¹³n. cm^?2. sec^?1 and the irradiation is done for 72–96 hours. using large Ge(Li) detectors (100 to 150cc) and long counting time (8–16 hours) they measured 22 elements in concentrations below ppb and 10 others between ppb and 300 ppm. Trace elements in germanium have been determined both instrumentally after very long decay time (100 days) or after short decay time removing the activities from the matrix by chemical separation. Trace elements in GaAs are determined only after chemical separtion. Several other semiconductor material such as Sc, Te, GaP and CuInS₂ were also determined by NAA. Some trace elements cannot be determined by neutron activation. Carbon, nitrogen and oxygen are determined by activation with protons, alphas or ³He particles. Boron and hydrogen are determined by prompt emission induced by charged particle activation, which gives not only the total concentration but also the depth profile. Carbon, nitrogen, oxygen and phosphorus were also determined by prompt proton activation analysis. The environmental samples studied by activation analysis can be divided into three categories: atmospheric aerosols, water samples and solid wastes. NAA of atmospheric aerosols have been used for their posible toxicological hazards, their source identification and for studies of atmospheric transport processes.     

Determination of 34 elements in Chinese geochemical standard reference materials by instrumental neutron activation analysis

Thirty four elements (Al, As, Ba, Br, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Gd, Hf, Ho, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, Ti, U, V, W, Yb) were determined by instrumental neutron activation analysis in the second set of Chinese geochemical standard reference materials (sediments from GSD-9 to GSD-12, soils from GSS-1 to GSS-8, rocks from GSR-1 to GSR-6) using both thermal and epithermal irradiations. Irradiation schemes designed to utilise short, medium and long-lived nuclides were employed in order to analyse major, minor and trace elements with different half-lives. The gamma-ray spectra were measured by Ge(Li) and HP(Ge) detectors. Relevant nuclear data and possible interferences are listed, and analytical results are presented and discussed.     

An internal standard method for the determination of trace elements in cigarette tobacco by neutron activation analysis

An internal standard method has been applied for the determination of lanthanum, antimony, scandium, chromium, iron and cobalt in commercial cigarettes by neutron activation analysis using gold as an internal standard element. These trace elements were separated from irradiated samples by APDC (ammonium pyrrolidine dithiocarbamate)/Zeph (tetradecyl dimethyl benzyl ammonium chloride) coprecipitation, followed by direct gamma-counting of the separated precipitate using a Ge(Li) detector. Standard reference tobacco 1R1 prepared by the University of Kentucky was also analyzed by this procedure for the above 6 elements, the results of which were compared with literature values. Good results were obtained by the present method.     

Determination of trace impurities in platinum by neutron activation analysis

Determination of trace impurities in platinum by neutron activation analysis was carried ont by combining the advantages of ion exchange chromatography and Ge(Li spectrometry. Owing to the development of a new ion exchange separation scheme which assures high decontamination factors with respect to matrix activities and practically quantitative yields, ppm and sub ppm amounts of Au, Cu, Ir, K, La, Mn, Pd and Zn were determined in 10 mg samples of pure platinum metal. No determinations of the chemical yield were necessary. Several other elements could be determined, if present, without essentially changing the procedure.     

Routine multielement instrumental neutron activation analysis of silicate rocks using short-lived radionuclides

By means of thermal neutron activation and countings on the small planar and large coaxial Ge(Li) detector, 13 elements are determined in various silicate rocks, using short-lived radionuclides with half-lives from 2 min to 15 h. A method of routine analysis with simple dead-time and pile-up correction is described and tested with the standard rocks AGV-1 and G-2.     

Application of neutron activation analysis to determine the contents and isotopic ratios of elements in rocks and minerals

Data on the applicability of neutron activation analysis to determine various rare and trace elements and the isotopic abundance of some of them in natural samples are discussed as relevant to the solution of various geological and geochemical problems. For the determination of minute amounts of elements from small weighed quantities of rocks and minerals a number of modifications of neutron activation analysis are used: analysis with the radiochemical separation of individual elements—RNAA (tantalum, tungsten, antimony, arsenic, molybdenum, rhenium, osmium, etc.) and analysis with semiconductor—Ge (Li)—gamma-spectrometry, which is multi-element and non-destructuve—INAA (scandium, europium, tantalum, iron caesium, rubidium, cobalt, antimony, etc.) or the combination of the latter with group radiochemical separation—IRNAA (alkaline, alkaline-earth, rare-earth elements, etc.). First steps have been made towards developing techniques for the determination of the isotopic rations of some elements by means of neutron activation method, e.g., the isotopic ratio of⁵⁸Fe/⁵⁴Fe. The accuracy of isotopic ratio determination is 1 to 3 relative per cent.     

Determination of trace elements in Iranian cigarette tobacco by neutron activation analysis

The concentration of 24 trace elements in the tobacco of two different brands of Iranian cigarettes, “Zarrin” and “Oshnoo”, has been measured by neutron activation analysis employing a high-resolution Ge(Li) detector. These elements are: Na, K, Sc, Cr, Mn, Fe, Co, Zn, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Eu, Tb, Hf, Au, Hg and Th.     

Fast neutron activation analysis: High resolution gamma spectroscopy

The purpose of this study was to demonstrate the versatility of combining the use of high resolution, Ge(Li) γ-detectors with the techniques of fast neutron activation analysis. A compilation of γ-ray spectra are presented for irradiation of 30 elements with 14.8 MeV neutrons under standard conditions and the origin of all major photopeaks is determined.     

An activation analysis technique for determining groups of trace elements in rocks and chondrites

A thermal neutron activation analysis technique has been developed for the analysis of terrestrial rocks and stony meteorites for trace elements. The main emphasis of the method is directed toward minimizing chemical procedures and maximizing the use of Ge(Li) gamma spectroscopy and computer data reduction. The validity of the technique is demonstrated by presenting data obtained for synthetic samples, U.S G.S. Standard Rocks and three ordinary chondrite meteorites for the following elements: As, Au, Co, Cs, Ga, Ge, Hg, Mo, Os, Re, Sb, Sc, Se, Te and Zn. Submitted in partial fulfillment of the requirements for the Ph. D. degree in the Department of Chemistry, Purdue University.     

Activation analysis of alkaline rocks. A comparison between destructive and non-destructive methods

The United States Geological Survey reference sample AGV-1 andesite, and three alkaline rocks from the apatite mine of Jacupiranga, Brasil, were analyzed by thermal neutron activation analysis using destructive and non-destructive methods, and high resolution Ge(Li) gamma-ray detectors. One of the rocks, a carbonatite, was also analyzed by instrumental activation analysis with epithermal neutrons. A greater number of elements can be determined using the radiochemical separation, but the precision and accuracy attained by INAA and RNAA were of the same order for most of the elements analyzed. Epithermal activation was more advantageous for tantalum, terbium and holmium. Comparison of the analytical results for USGS reference sample (AGV-1) with the data published by others gave good agreement. Statistical tests used for comparison of the results of destructive and non-destructive methods, as well as other results are presented.