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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Alrakabi, G. Singh, A. Bhalla, S. Kumar, S. Kumar, A. Srivastava, B. Rai, N. Singh, J. Shahi, and D. Mehta

Abstract  

The elemental concentration of uranium in the samples collected from the ground water and the canal water in the Bathinda district of Punjab state, India, have been investigated using X-ray fluorescence technique. The residues obtained after drying the water samples were analysed using the energy dispersive X-ray fluorescence spectrometer consisting of Mo-anode X-ray tube equipped with selective absorbers as an excitation source and an Si(Li) detector. The uranium concentration values in significant fraction of the shallow ground water samples from the hand pumps is found to be above the permissible level of 15 ppb recommended by World Health Organisation for the drinking water, and its values in the canal water samples are below 5 ppb. To investigate the flyash from the coal-fired thermal power plants as a possible source of ground water contamination, the water samples collected from the surroundings of the power plants and the flyash samples were also analyzed. The results rule out flyash as a source of uranium contamination. Agrochemical processes occurring in the calcareous soils in the region are the favoured potential source of uranium contamination of the ground water.

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Abstract  

The potentiality of portable instrumentation lies on the possibility of the in situ determinations. Sampling, packaging and transport of samples from the site to the laboratory are avoided and the analysis becomes non destructive at all. However, detection limits for light elements are, in most cases, a limitation for quantification purposes. In this work a comparison between the results obtained with an X ray fluorescence spectrometer laboratory based and a portable instrument is performed. A set of 76 obsidian archaeological specimens from northwest Patagonia, Argentina was used to carry out the study. Samples were collected in the area of the middle and high basin of the Limay River. The analytical information obtained with both instrumentations was complemented with Principal Component Analysis in order to define groups and identify provenance sources. The information from both instruments allows arriving to the same conclusion about sample provenance and mobility of hunter-gatherer groups. Three groups of sources were identified in both cases matching with the geographical information. Also, same sets of outlier samples or not associated to these sources were found. Artifact samples were associated mainly to the closest sources, but some of them are related to sources located more than three hundred kilometers, evidencing the large mobility of the hunter-gatherers by the obsidian interchange. No significant differences between concentrations values obtained by laboratory based instrument and portable one were found.

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Abstract  

Problems involved in developing radioisotope sources and the characteristics of potentially useful radioisotopes for X-ray fluorescence analysis are presented. Some of the isotopes, which are not in use but look very promising, are indicated.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Ashok, T. Rautray, Pranaba Nayak, V. Vijayan, V. Jayanthi, and S. Narayana Kalkura

Abstract  

The elemental analysis of south Indian gallstones has been carried out using energy dispersive X-ray fluorescence (EDXRF) spectroscopy. A number of important elements including Fe, Cu, Zn, Br, and Pb were estimated from the EDXRF spectra. The results are presented and discussed.

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Abstract  

Coal samples were analysed for trace elements using total reflection X-ray fluorescence with monochromatic excitation. The procedure involved direct irradiation of the sample with the incoherent peak as internal standard. A new method for spectrometer sensitivity determination and sample quantification, was evaluated. Variable amounts of several trace elements were obtained in the analysis of coal from eight different deposits of Mongolia. The accuracy of the procedure was verified with the analysis of a coal standard.

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Abstract  

The rapid assay of the trace multi-element content of environmental samples (lake sediment) is described. The method utilized X-ray fluorescence induced by a109Cd radioisotopic source with energy dispersive quantitative detection of the characteristic X-rays of nine elements, ranging from Ti to Zr using Si(Li) semiconductor detector. The method precludes pre-digestion or chemical treatment of the samples, and compairs favorably with the results of atomic absorption assay methods.

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Abstract  

Twenty ancient silver coins have been analyzed by the X-ray fluorescence method. For eliminating the effects that disturb the absolute quantitative measurements, we calculated, for each coin, the ratio between the elements that constitute the coin and related them to the silver concentration. From these measurements correlation diagrams have been obtained in which coins are grouped together depending on the silver sources and the purification technologies.

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Abstract  

Advantages of X-ray fluorescence with the use of Synchrotron Radiation are emphasized (intensity, polarization, tunability of energy). The experimental set-up and the fast computer system for the data reduction without standards are presented. The results are in good agreement with standard references. Examples of applications are presented: old coins and potteries were studied in archaeological domain; metal alloys were analyzed; element composition of bulk samples of volcanic rocks, sublimates and aerosols were determined.

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Abstract  

A method for analyzing U and Th in radioactive ores by radioisotope excited X-ray fluorescence is described. For the proposed analysis, the theoretical and experimental factors that affect the sensitivity of the radioisotope XRF technique were investigated. Minimum detection limits of 13 ppm and 108 ppm can be achieved for U and Th, respectively, with a total counting time of 1000 s on a powdered ore sample. Results obtained in the analyses of radioactive ores from Turkey and BL-5 candidate reference uranium ores from CANMET (Canada Centre for Mineral and Energy Technology) are reported.

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Abstract  

X-ray fluorescence (XRF) has reached a mature state and represents a powerful analytical tool for the qualitative and quantitative determination of almost all the chemical elements in a sample. Standard XRF methods as well as special techniques to improve the detection limits will be presented, emphasizing the versatility of the method. With modern instrumentation the detectable number of elements ranges from Be to U. The minimum detectable quantities under optimizied excitation and detection conditions for medium Z elements are a few hundred femtograms. Other features like rapid analysis because of the multielement capability and in some cases the nondestruction of the sample are advantageous for a wide field of applications.

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