Rare-earth elements in Egyptian granite by instrumental neutron activation analysis.

The mobilization of rare-earth elements (REEs) in the environment requires monitoring of these elements in environmental matrices, in which they are mainly present at trace levels. The similarity in REEs chemical behavior makes the separate determination of each element by chemical methods difficult; instrumental neutron activation analysis (INAA), based on nuclear properties of the elements to be determined, is a method of choice in trace analysis of REEs and related elements. Therefore, INAA was applied as a sensitive nondestructive analytical tool for the determination of REEs to find out what information could be obtained about the REEs of some Egyptian granite collected from four locations in Aswan area in south Egypt as follows wadi El-Allaqi, El-Shelal, Gabel Ibrahim Pasha and from Sehyel Island and to estimate the accuracy, reproducibility and detection limit of NAA method in case of the given samples. The samples were properly prepared together with standards and simultaneously irradiated in a neutron flux of 7 x 10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The following elements have been determined: La, Ce, Nd, Sm, Eu, Yb and Lu. The gamma spectra was collected by HPGe detector and the analysis was done by means of computerized multichannel analyzer. The X-ray fluorescence (XRF) was also used.     

Characterisation of firearms and bullets by instrumental neutron activation analysis

Instrumental neutron activation analysis was adopted to investigate the chemical composition of lead and jacketed firearms bullets.Analyses have been carried out on the most used bullets according to calibre and manufacture.The trace element content of the bullets (center and jacket) and of fragments of bullets has been utilised to identify the manufacturer.Bullets from the same manufacture have been analysed to differentiate different batches in production.     

Characterization of ophiolites from northern Havana-Matanzas petroleum fields using instrumental neutron activation analysis.

Concentrations of 16 elements from 14 serpentinitic samples from Basilio and Cantel petroleum fields were obtained by instrumental neutron activation analysis (INAA): Cr, Co, Ni, La, Nd, Sm, Eu, Gd, Tb, Ce Yb, Lu, Rb, Cs, Hf and Th. Relative INAA was performed using certified reference materials and laboratory standards. Average elemental concentrations showed that the ophiolites have a basic character, suggesting the use of a well-logging method designed for volcano-sedimentary petroleum fields.     

The determination of platinum in biological tissue by instrumental neutron activation analysis

Neutron activation analysis was used to determine platinum in the tissues of rats that had received doses of the tumor chemotherapy agent cis-Pt. Two elements causing spectral interference were identified as ⁴⁷Sc from ⁴⁶Ca, a natural component of tissue, and tin (^117mSn), an element introduced inadvertently during necropsy and sample work-up. A protocol was devised to correct for interference, using emission lines from ⁴⁷Ca and ¹¹³Sn, respectively, with appropriate consideration for relative detector efficiencies, decay times and half-lives.     

Heavy metals and rare earth elements in phosphate fertilizer components using instrumental neutron activation analysis.

The technique of instrumental neutron activation analysis was applied as a sensitive nondestructive analytical tool for the determination of heavy metals and rare earth elements in phosphate fertilizer ingredients. The contents of heavy metals Fe, Zn, Co, Cr and Sc as well as rare earth elements La, Ce, Hf, Eu, Yb and Sm were determined in four samples representing the phosphate fertilizer components (e.g. rock phosphate, limestone and sulfur). These samples were collected from the Abu-Zabal phosphate factory in El-Qalubia governarate, Egypt. The aim of this study was to determine the elemental pattern in phosphate ingredients as well as in the produced phosphate fertilizer. Fair agreement was found between the results obtained for the standard reference material Soil-7 and the certified values reported by the International Atomic Energy Agency. The results for the input raw materials (rock phosphate, limestone and sulfur) and the output product as final fertilizer are presented and discussed.     

The determination of calcium in faecal samples by instrumental fast neutron activation analysis

A method is described for the determination of calcium in faecal material by a purely instrumental technique, namely fast neutron activation analysis. The major advantage of the technique over existing methods is that it requires minimal sample preparation. In addition, only a single standard is used and the method is also fairly rapid and simple. The method is well suited to the routine analysis of large numbers of samples and the results are shown to be comparable with atomic absorption spectrophotometry in accuracy. Finally, the technique can be extended to include the determination of several other elements providing a standard for each element is included.     

Factor for correcting the ruthenium interference in instrumental neutron activation analysis of barium in uraniferous samples

The fission spectral interference of ruthenium on the instrumental neutron activation analysis of barium in samples containing uranium is extensively discussed. In particular the dependence of the correction factor on the Φ_epi/Φ_th ratio is studied. An excellent agreement between experimental and calculated values is achieved. A procedure is suggested for the resolution of multiple interferences in the general case where uranium, barium and/or ruthenium are present in samples to be analysed.     

Multielement analysis of human hair and kidney stones by instrumental neutron activation analysis with the k0-standardization method.

This paper focuses on the evaluation of the k₀ method of instrumental neutron activation analysis in biological materials. The method has been applied in multielement analysis of human hair standard reference materials from IAEA, No. 085, No. 086 and from NIES (National Institute for Environmental Sciences) No. 5. Hair samples from people resident in different parts of Malaysia, in addition to a sample from Japan, were analyzed. In addition, human kidney stones from members of the Malaysian population have been analyzed for minor and trace elements. More than 25 elements have been determined. The samples were irradiated in the rotary rack (Lazy Susan) at the TRIGA Mark II reactor of the Malaysian Institute for Nuclear Technology and Research (MINT). The accuracy of the method was ascertained by analysis of other reference materials, including 1573 tomato leaves and 1572 citrus leaves. In this method the deviation of the 1/E¹⁺ epithermal neutron flux distribution from the 1/E law (P/T ratio) for true coincidence effects of the γ-ray cascade and the HPGe detector efficiency were determined and corrected for.     

Elemental analysis of two Egyptian phosphate rock mines by instrumental neutron activation analysis and atomic absorption spectrometry

Because of the increasing use of phosphate in industry world wide, it is interesting to investigate the elemental concentration in phosphate ores. The present work determines the elemental analysis of two different types of phosphate ores, containing different amounts of P₂O₅ to check the level of the radioactive elements U and Th and of stable environmental pollutants like Cr, Zn in phosphate raw material. In addition, rare earth and other elements are analysed by the INAA method. This knowledge is found to be important in the assessment of possible radiological hazards to human health, since these materials may be used as building material or as phosphatic fertilizers and animal feed ingredients.     

Comparison between different types of glass and aluminum as containers for irradiation samples by neutron activation analysis.

Three different types of glass and four different kinds of aluminum sheet have been analyzed using neutron activation analysis. The irradiation facilities of the first Egyptian research reactor (ET-RR-1) and a hyper-pure germanium (HPGe) detection system were used for the analysis. Among the 34 identified elements, the isotopes 60Co, 65Zn, 110mAg, 123mTe, 134Cs, 152Eu and 182Ta are of special significance because of their long half-lives, providing a background interference for analyzed samples. A comparison between the different types of containers was made to select the preferred one for sample irradiation.     

Salvinia auriculata: aquatic bioindicator studied by instrumental neutron activation analysis (INAA).

Through instrumental neutron activation analysis (INAA) the elemental chemical composition of Salvinia auriculata and Ouro Preto city public water was determined. Elements Ce, Th, Cr, Hf, Sb, Sc, Rb, Fe, Zn, Co, Au, La and Br were quantified. High chromium concentration was determined in this plant. But, chromium was determined only in low concentrations in the water. The results indicate the great capacity of this plant to absorb and accumulate inorganic elements.     

Elemental analysis of granite by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF)

The instrumental neutron activation analysis technique (INAA) was used for qualitative and quantitative analysis of granite samples collected from four locations in the Aswan area in South Egypt. The samples were prepared together with their standards and simultaneously irradiated in a neutron flux of 7×10(11)n/cm(2)s in the TRIGA Mainz research reactor. Gamma-ray spectra from an hyper-pure germanium detector were analyzed. The present study provides the basic data of elemental concentrations of granite rocks. The following elements have been determined Na, Mg, K, Fe, Mn, Sc, Cr, Ti, Co, Zn, Ga, Rb, Zr, Nb, Sn, Ba, Cs, La, Ce, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. The X-ray fluorescence (XRF) was used for comparison and to detect elements, which can be detected only by XRF such as F, S, Cl, Co, Cu, Mo, Ni, Pb, Se and V. The data presented here are our contribution to understanding the elemental composition of the granite rocks. Because there are no existing databases for the elemental analysis of granite, our results are a start to establishing a database for the Egyptian granite. It is hoped that the data presented here will be useful to those dealing with geochemistry, granite chemistry and related fields.     

Characterization of neutron flux spectra in irradiation sites of MNSR reactor using the Westcott-formalism for the k0 neutron activation analysis method.

For the general applicability of the k0-NAA method to deal with "non-l/v" (n,gamma) reaction nuclides, the modified spectral index r(alpha) square root (Tn/T0) and g(Tn) factor for monitoring neutron temperature Tn for the inner and outer irradiation sites of the Ghana MNSR reactor (GHARR-1) were measured using the Cd-ratio method. Using the measured Cd ratio for lutetium and the modified spectral index, the reduced resonance integral of lutetium s0,Lu was also calculated. The computed result of 1.64 was in good agreement with the reported value of 1.67. Based on the assumption that the definitions of reaction rates in the Westcott-formalism and in Nisle's unified formulation are equal, a theoretical verification of the accuracy of the measured modified spectral indices for our data and those reported in the literature for other research reactors was carried out. Employing 197Au, 96Zr and 94Zr as "1/v" monitors, the theoretical values which depend on the choice of the monitor, followed the trend for measured values of the sub- to epi-cadmium flux ratio f for nine irradiation sites of four different research reactors. The computed and experimental modified spectral indices for the different flux ratios associated with irradiation sites within the range 18.8-152 fitted well to a simple exponential relationship. Calculated and measured data are in good agreement when appropriate correction factors are used.     

The use of instrumental neutron activation and multivariate statistic analyses in differentiation of Brazilian phosphate ores.

Phosphated rocks from three ores located in the Middle-West region of Brazil can be used as low-level radioactive reference material due to the fact that they contain significant concentrations of thorium and, in some cases, of uranium. This paper describes the procedure to characterise those samples using several analytical methods. Statistical analysis and correlations studies have shown several geochemical similarities and the results obtained suggest the possibility to produce a reference material composed of a mixture of two similar ores.     

Monte Carlo simulation of neutron irradiation facility developed for accelerator based in vivo neutron activation measurements in human hand bones.

The neutron irradiation facility developed at the McMaster University 3 MV Van de Graaff accelerator was employed to assess in vivo elemental content of aluminum and manganese in human hands. These measurements were carried out to monitor the long-term exposure of these potentially toxic trace elements through hand bone levels. The dose equivalent delivered to a patient during irradiation procedure is the limiting factor for IVNAA measurements. This article describes a method to estimate the average radiation dose equivalent delivered to the patient's hand during irradiation. The computational method described in this work augments the dose measurements carried out earlier [Arnold et al., 2002. Med. Phys. 29(11), 2718-2724]. This method employs the Monte Carlo simulation of hand irradiation facility using MCNP4B. Based on the estimated dose equivalents received by the patient hand, the proposed irradiation procedure for the IVNAA measurement of manganese in human hands [Arnold et al., 2002. Med. Phys. 29(11), 2718-2724] with normal (1 ppm) and elevated manganese content can be carried out with a reasonably low dose of 31 mSv to the hand. Sixty-three percent of the total dose equivalent is delivered by non-useful fast group (> 10 keV); the filtration of this neutron group from the beam will further decrease the dose equivalent to the patient's hand.     

Determination of natural radioactivity in building materials used in the Rawalpindi/Islamabad area by gamma-ray spectrometry and instrumental neutron activation analysis.

Samples of sand and manufactured building materials collected from the Rawalpindi/Islamabad area have been analyzed for the primordial natural radionuclides 238U, 232Th and 40K using gamma-ray spectrometry. The uranium and thorium contents have also been determined by instrumental neutron activation analysis (INAA). The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The comparison shows that, of the nine samples analyzed, only the three brick samples have higher activities than the world averages for soil. The specific activities in these materials, having a radium equivalent activity of less than 370 Bq kg-1, when evaluated for radiological effects show that all materials meet the external gamma-ray dose limitation of 1.5 mSv y-1. The gamma-spectrometric and INAA techniques complemented each other well in this study.     

Simultaneous determination of mineral nutrients in different varieties of wheat and Bengal gram in India by instrumental neutron activation analysis

Instrumental neutron activation analyses (INAA) of different varieties of wheat and Bengal gram in India have been performed with a 2 Ci ²⁵²Cf fission neutron source for their mineral nutrient content. The percentages of potassium, sodium and manganese in Bengal gram dhal and in its husk as well as that of sodium and manganese in different wheat samples are determined by measuring the γ activity of radioisotopes formed after (n,γ) reaction at the corresponding photo peak using an 8 K multichannel analyzer coupled with a high purity germanium (HPGe) detector.