Chemical characterization of Yapese clays and ceramics by instrumental neutron activation analysis

Chemical-characterization data from INAA provided information for understanding procurement of clays and production of ceramics in the Yapese past. By integrating mineralogical and chemical composition studies, we suggest clay-source zone distinctions for the different Yapese ceramic wares. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chemical characterization of gas- and oil-bearing shales by instrumental neutron activation analysis

The concentration of As, Ba, Ca, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, K, La, Lu, Mn, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, and Zn were determined by instrumental neutron activation analysis in block shale samples of the New Albany Group (Devonian-Mississippian) in the in the Illinois Basin. Uranium content of the samples was as high as 75 ppm and interfered in the determination of samarium, molybdenum, barium and cerium. In the determination of selenium a correction was made for interference from tantalum. U, As, Co, Mo, Ni and Sb as well as Cu, V and pyritic sulphur which were determined by other methods, were found to correlate positively with the organic carbon content of the samples.     

Chemical characterisations of Anatolian obsidians by instrumental and epithermal neutron activation analysis

Obsidian is a volcanic glass which is generally black, sometimes grey, brown, red or green in colour and characterised by a glassy appearance and conchoidal fractures. It is formed by the sudden cooling of the molten, generally acid magma with high water content. Obsidian was widely used for tool-making during prehistoric times. This work concems the chemical characterisation of obsidian occurrences from Northem, Central and Eastem Anatolia by Instrumental and Epithemal Neutron Activation Analysis for obtaining an accurate fingerprint for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts.     

Elemental characterization of bread and durum wheat by instrumental neutron activation analysis

Cereals are by far the most significant agricultural crops, not only due to the sheer amount of their gross-tonnage production and prevalence in human diets worldwide, but also as food vehicles of important items for human nutrition and wellness at large—proteins, dietary fibers and oligoelements, such as selenium, calcium, zinc and iron, to name just a few. Still, some micronutrients feature an uneven distribution in the upper continental crust, and thus in cultivation soils deriving therefrom. Whether soils have always been poor in an essential element, or have just become deprived of it by intensive farming, the result is the same: insufficient soil–plant transfer, feeble-to-nonexistent plant uptake, and, therefore, unsatisfactory dietary distribution of that element through the food chain. Countries that implemented corrective measures or programs of crop biofortification and consumer education have been successful in dealing with some micronutrients’ deficiencies. Given their relative weight in Portuguese diets, cereals are obvious candidates for crop-supplementation strategies that may contribute to an upgrade in the health status of the whole population. A good knowledge of element-baseline data for major cereal varieties (plants) and main production areas (soils) is a pre-requisite though. The present work was aimed at an elemental characterization of cereals and soils from relevant wheat-producing areas of mainland Portugal. This paper is focused on wheat samples—bread and durum wheats; Triticum aestivum L. (Farak and Jordão cultivars) and Triticum durum Desf. (Don Duro and Simeto cultivars), respectively—from the 2009 campaign, collected at Trás-os-Montes, Alto Alentejo and Baixo Alentejo (inland regions). Elemental concentrations were determined by instrumental neutron activation analysis (INAA; k ₀-variant), and assessed with the k ₀-IAEA software. Quality control was asserted through the analysis of NIST-SRM^® 1567a (Wheat Flour), NIST-SRM^® 1568a (Rice Flour) and GBW 07404 (Limy-yellow Soil). Results are discussed and compared to available data from abroad.     

Trace characterization of high-purity nickel by instrumental and radiochemical neutron activation analysis

Summary The high activity of the radionuclides ⁶⁵Ni (t_1/2=2.52 h) and ⁵⁸Co (t_1/2=70.8 d) imposes severe limitations on the performance of direct instrumental neutron activation analysis of nickel. The extent of the interference of the ⁵⁸Co depends on the ratio of the fluxes of the fast and thermal neutrons. A method of selective removal of cobalt, based on extraction with -nitroso--naphthol has been developed for the purpose of radiochemical NAA. Separation yields have been determined for 36 elements. The detection limits obtainable with both the instrumental and the radiochemical method are <10^–4 g/g for the elements Au, Eu, Ir, La, Sc and Sm, between 10^–4 and 10^–3 g/g for Cr, Cs, Hf, Hg, Lu, Re, Sb, Ta, Th, Tm and Yb, between 10^–3 and 10^–2 g/g for As, Ag, Br, Ce, Ga, Na, Ru, Se, W and Zn, and in the range 0.01–1 g/g for Ba, Cd, Co, Fe, In, K, Mo, Nd, Pd, Rb, Sn, U and Zr.     

Multielement analysis of lichen by instrumental neutron activation analysis

Lichen (species Trypethelium Eluteriae) is analysed for different elements. Nondestructive instrumental neutron activation analysis is employed for the multielemental analysis. Gamma-ray spectrometry is used for the identification and quantitative estimation of elements. Concentrations of 24 elements are reported. Gamma-ray spectrum of the lichen irradiated for 16 hours, delayed for 10 days, and counted for 10 hours on a 50 cm³ coaxial Ge(Li) detector is given.     

Elemental analysis of limestone by instrumental neutron activation analysis

Limestone samples from Assuit Governrate in Upper Egypt were subjected to elemental analysis by instrumental neutron activation analysis and X-ray fluorescence techniques. The samples were properly prepared together with their standards and simultaneously irradiated in a neutron flux of the order 7 × 1011 n/cm² s using TRIGA research reactor at Mainz. After activation the samples were subjected to γ-ray spectrometry using a high purity germanium detection system and computerized multichannel analyzer. Nineteen elements: Na, Ca, Mn, Fe, Sc, Cr, Co, Zn, Sn, La, Ce, Nd, Eu, Sm, Yb, Lu, Hf, Th and U were analyzed. X-ray fluorescence spectrometry have been also used. The presence of any elements in higher or lower levels in certain limestone samples is contingent on the occurrence of its bearing minerals, nature of parent sediments and depositional environments of these sediments. The major elements in the samples were also observed to be among the elements that had high enrichment factors in the study of suspended dust particulate within and around cement industries. This confirms cement as the major contributor to the airborne particulate matter in the environs.     

Chemical characterisations of Carpathian obsidian sources by instrumental and epithermal neutron activation analysis

Obsidian samples from the Tokaj Mountains (Hungary) and from the neighbouring Zemplin Hills (Slovakia) were analysed by instrumental and epithermal neutron activation analysis for obtaining a “fingerprint” for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts. These techniques fully discriminate the Zemplin Hills sources (Carpathian I, eastern Slovakia) and the Tokaj Mountain sources (Carpathian II, north-eastern Hungary) as well as these Central European sources from those already studied of the Mediterranean basin and adjacent regions.     

Multielemental analysis of soils by instrumental neutron activation analysis

The results of an instrumental neutron activation analysis of some elemental concentrations in different soil samples near the industrial areas at Tirupati, India, are reported. Altogether 14 elements, Sm, La, Cr, Co, Zn, Cs, Ce, Th, Rb, Na, K, Sr, Fe and Eu were determined. The samples were irradiated with neutrons at the 100 kW Triga - Mainz research reactor and the induced activities were measured by gamma-ray spectrometry using an efficiency calibrated high resolution high purity germanium (HPGe) detector in connection with a multichannel analyzer. The results are discussed.     

Determination of lithium by instrumental neutron activation analysis

The fast transfer system in the DR 2 reactor for irradiation at a thermal neutron flux density of 10¹³ n·cm⁻²·sec⁻¹ was used for the determination of lithium by the⁷Li(n, γ)⁸Li reaction. β-counting with a large perspex Cerenkov detector begun at 0.3 s after the end of irradiation, and multi-scaler data was accumulated in 300 channels at 0.1 s per channel. With a suitable choice of discrimination level only¹⁶N and background interfere, and the 0.84 s half-life of⁸Li was resolved by the method of weighted least squares. Results are presented for 36 international geochemical reference materials, and for a few biological samples, including BOWEN's kale and the NBS Standard Reference Material 1571 Orchard Leaves.     

Erros in instrumental neutron activation analysis

Equations are derived for the statistical and systematic error in INAA. It is possible to use them for the definition of limits of decision, detection and determination.     

Multi-element analysis of soils by computerized instrumental neutron activation analysis

The applicability of instrumental neutron activation analysis (INAA) for soils is described and demonstrated and its restrictions mentioned.     

Multielement analysis of food spices by instrumental neutron activation analysis

Twenty-four elements in six food spices were estimated by non-destructive instrumental neutron activation analysis. The problems in determining Cu were discussed.     

Errors in instrumental neutron activation analysis

Equations are derived for the statistical and systematic error in INAA based on single photopeaks. They may serve to predict the applicability of the method or to judge data obtained under well-known conditions.     

Multielement determination in water by instrumental neutron activation analysis

Instrumental neutron activation analysis /INAA/ technique has been applied to a water sample to determine the elemental concentrations. The sample was irradiated with a neutron flux of 1.2×10¹² n cm^–2 s^–1 for two different periods followed by counting at three different decay times, using two coaxial type high-resolution Ge/Li/ detectors. The dominant elements determined in the water sample are Ca, Cl, Na, Mg, and K present in ppm-level while Co, I, Mn, Sm, and Sb are present in smaller amounts, approximately on the average 0.01 ppm. Only traces of other elements such as the rare-earth elements, Ag, As, Ba, Cu, Cd, Fe, Sr, W, Zn, seem to be present in the water sample.     

Multielement analysis by sequential instrumental and radiochemical neutron activation

We measured 37 elements in six USGS geological camples and one NBS biological orchard leaf (OL) sample, using sequential INAA and radiochemical group separation coupled with high resolution, high efficiency Ge(Li), and a Ge(Li) with anticoincidence shields. The elemental concentrations in these samples vary over three orders of magnitude. Our results agree very well with the reported values. The rare earth values in PCC-1 are 2–4 times lower than the reported values. Precise REE patterns are defined in USGS samples, which are characteristic of the total rock types. The REE pattern in OL is identical to the mineral apatite. In addition to the possibility that OL may be contaminated by local soil, it is also possible that the uptake of REE trace elements by plants from soil is perhaps dominated by accessory mineral such as apatite, or plants take up the REE from bulk soil in a preferential manner as a smooth function of the REE ionic radii.     

Industrial applications of instrumental neutron activation analysis

Neutron activation analysis is shown as a useful diagnostic technique in semiconductor industry. A better acceptance of the method for applications in industry has been achieved through a specialized analytical service. Its main application is the characterization of high purity silicon in all stages of production. Irradiation of large sample volumes allowes a very sensitive detection of impurities in silicon with detection limits down to 10^–16 g/g. Other applications discussed are the analysis of silicon carbide, quartz, pure water and titanium. Special techniques described are autoradiography, depth profiling and surface analysis. In semiconductor process technology NAA was used to monitor contamination of silicon wafers.     

Rare-earth elemental analysis of banded iron-formations by instrumental neutron activation analysis

Representative banded iron-formations (BIFs) from various locations of the eastern Indian geological belt were investigated by instrumental neutron activation analysis (INAA). After pre-concentration, irradiation was carried out using a neutron flux of 5.1·10¹⁶ m⁻²·s⁻¹, 1.0·10¹⁵ m⁻²·s⁻¹ and 3.7·10¹⁵ m⁻²s⁻¹, with thermal, epi-thermal and fast neutrons, respectively. The activities in these samples were measured by a HPGe detector. Ten rare-earth elements, such as La, Ce, Nd, Sm, Eu, Tb, Ho, Tm, Yb and Lu, have been qualitatively identified and quantitatively estimated in these samples. The present investigation is an example of employing a pre-concentration method for high iron-containing ores prior to neutron activation analysis.     

Multi-element analysis of Ghanaian crude oils by instrumental neutron activation analysis

Instrumental neutron activation analysis based on thermal neutrons from the Ghana Research Reactor-1 facility was utilized to analyze 18 trace elements namely Al, As, Br, Ca, Cd, Cl, Co, Cu, Fe, K, Mg, Mn, Na, Ni, S, Si, V, and Zn in two different crude oil samples from the Saltpond and Jubilee field in the Saltpond, Central region and Cape Three Points, Western region of Ghana, respectively. The sulfur concentration for both samples were low and within globally accepted range of 0.1–0.5%wt for sweet crude oil. The results of the elemental analysis showed that the two samples are relatively low in trace element concentrations compared to crude oils of other countries. Higher Fe concentration in the Jubilee crude oil indicates younger oil. The V/Ni ratios obtained for crude oils from both locations imply a possible marine organic origin and also suggest the Saltpond crude oil is more matured than the Jubilee crude oil.     

Multielement analysis of Northwestern Nigerian rocks by instrumental neutron activation analysis

Rock samples from seven different locations in northwestern Nigeria were analyzed by reactor instrumental neutron activation analysis and Ge(Li) gamma-ray spectrometry. Concentration values were obtained for 18 elements (As, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Sc, Sm, Sr, Ta, Tb, Th, U, Yb). The geochemical implications of the results are discussed.