共查询到20条相似文献,搜索用时 15 毫秒
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《Spectrochimica Acta Part B: Atomic Spectroscopy》1999,54(10):1517-1524
The potential of a prototype grazing-emission X-ray fluorescence spectrometer for reliable analysis of sample solutions, obtained by pressurized microwave oven digestion of Si-spiked organic and biological materials, was investigated as part of an inter-laboratory study. The fact that this grazing-emission technique is based on the total reflection phenomenon and wavelength-dispersive detection, gives it the benefit to determine light elements in a sensitive way. Results of the determination of silicon in pork liver, cellulose, urine, serum, spinach, beer, mineral water and horsetail (dry plant extract) samples are presented. Some of the results are compared with those obtained with other analytical techniques. The study proved that determination of silicon traces in biological matrices represents an extremely difficult task, however, measurements of silicon are achieved with acceptable precision. The most important problems still arise when sample pre-treatment is needed prior to analysis. 相似文献
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X射线荧光光光谱分析 总被引:3,自引:0,他引:3
评述了我国在2007~2008年X射线荧光光谱,包括质子激发的X射线光谱的发展和应用,内容包括仪器、软件、仪器改造、仪器维护和维修、基础研究和分析方法研究及其应用. 相似文献
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《Spectrochimica Acta Part B: Atomic Spectroscopy》1999,54(13):1881-1888
Ni ultra-thin films sandwiched with carbon thin films of different thickness are measured by a laboratory grazing-emission X-ray fluorescence instrument. The Ni Kα intensity of the Ni ultra-thin film sandwiched with carbon layers is three times enhanced in comparison with the Ni ultra-thin film without carbon layers. In addition, oscillations caused by interference effects of directly observed X-ray beams and the reflected X-ray beams on the surface of the Pt substrate, are clearly observed. The periods of the oscillations depends on the thickness of the carbon layer, that is, the position of the Ni layer. Therefore, the thickness of the carbon layer can be estimated. 相似文献
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Budesinsky BW 《Talanta》1976,23(3):211-215
Iron, magnetite, copper, copper(II) oxide, calcium carbonate, sulphur, silicon dioxide and aluminium oxide as components of copper intermediates (concentrates, slags, mattes, calcines and fluxes) in powdered (300-400 mesh) binary mixtures obey the Lachance-Traill equation, so the coefficients alpha(AX) of interelement effects can easily be determined experimentally. They show a reasonable agreement with the theoretical values calculated from mass absorption coefficients. This fact can be the basis of a convenient routine method for the determination of intermediates. Since the intermediates exhibit differences in the distribution of their atoms (microcosmic inhomogeneity) a correction factor k(dist) has to be used. Its value for the main components (concentrations > 5%) is in the range 0.92-1.24 The highest relative average deviation of the results from those of the classical "wet" methods is 2.7% for the major and 30% for the minor components. 相似文献
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X-ray fluorescence spectrometry (x.r.f.) can be done through excitation with synchrotron radiation. This permits multi-element determinations in the trace region with improved detection limits compared to conventional x.r.f. Detection limits are evaluated and compared with theoretically calculated values. For a beam diameter of 0.5 mm and a sample of 1 mg cm?2, absolute detection limits are between 0.1 and 0.4 pg. The dependence of the detection limit on the atomic number is reduced, when white synchrotron radiation is used for excitation instead of monochromatic radiation. The optimum of the limit of detection on the Z-scale can be shifted to higher atomic numbers and improved through filtration of the primary radiation by aluminium absorbers. Preparation of samples on different polymeric films is discussed in relation to blank values. 相似文献
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Peter Hoffmann Martin Kein Volker Scheuer Karl Heinrich Lieser 《Mikrochimica acta》1990,101(1-6):305-313
X-ray fluorescence spectrometry with total reflection conditions is applied in the qualitative and quantitative determination of impurities in thin layers of Ti, TiO2, and HfO2 prepared by evaporation and of SiO2, TiO2, and Ta2O5 prepared by ion beam sputtering. The same method is used to examine stainless steel discs, which have to be used as reference materials,Dedicated to Professor Günther Tölg on the occasion of his 60th birthday 相似文献
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A modified standard addition method for single element determination by X-ray fluorescence spectrometry has been studied. The attenuation properties of the standard added samples are kept constant by adding decreasing amounts of an attenuation modifier along with increasing amounts of a standard. In this way the standard addition curve will be a straight line in cases where the ordinary standard addition curve is non-linear, and linear regression can be used to evaluate the concentration of the analyte. Standard additions of oxides of a number of elements, with and without modifier, have been made to cellulose powder or a mixture of aluminium oxide and polyethylene as matrices in order to test the method. The method has been applied to the determination of zinc in fly-ash from a steel work and of iron in cement. The fly-ash contained about 5% of zinc and the cement samples between 2 and 5% of Fe(2)O(3). The results were compared with those obtained by ICP-AES after decomposition of samples in lithium tetraborate or lithium metaborate and dissolution of the melt in 10%(v/v) nitric acid. The results agreed within 2%, relative, for fly-ash and within 3-6%, relative, for cement samples. 相似文献
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《Spectrochimica Acta Part B: Atomic Spectroscopy》1997,52(7):829-840
In grazing-emission X-ray fluorescence spectrometry (GEXRF), the sample is irradiated at approximately normal incidence, and only that part of the fluorescence radiation is detected that is emitted at grazing angles. This configuration allows the use of wavelength-dispersive detection. This type of detection has the advantages of substantially better energy resolution at longer wavelengths (light elements, L and M lines of heavier elements) and a much larger dynamic range than the energy-dispersive detectors currently used in grazing X-ray techniques. Typical examples are presented of applications that are made possible by this new technique. 相似文献
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Five sample presentation techniques were examined for the X-ray fluorescence spectrometric analysis of tungsten carbide alloys in powder and cemented forms. Powder samples may be oxidized by air at 600° before fusion (I), or preferably by lithium nitrate during fusion (II); the fusion is effected with lithium-lanthanum tetraborate followed by briquetting with graphite. Powder samples may also be blended with wax and briquetted (III). Cemented carbides are surface-prepared with silicon carbide before analysis (V). Briquettes prepared by blending carbide powder, lithium-lanthanum tetraborate and graphite (IV), give poor reproducibility, however, owing to micro-absorption effects the technique is not recommended. The determination of eight common elements in tungsten carbide is discussed and the relative standard deviations are 0.002–0.004 for major and 0.008–0.01 for minor elements. 相似文献
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Vj. Novosel-Radović Da. MaljkoviĆ N. NenadiĆ 《Spectrochimica Acta Part B: Atomic Spectroscopy》1985,40(4):701-704
The paper deals with diminished wear resistance of standard samples in X-ray fluorescence spectrometry. The effect of X-ray irradiation on pellet samples, pressed with starch as organic binder, was investigated by sieve analysis and scanning electron microscopy. A change in the starch grain size was found as a result of swelling and cracking. 相似文献
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The determination of common wear metals, namely iron, chromium, copper, zinc and lead, in a wide range of lubricating oil samples was investigated for the use of a low-cost, wavelength-dispersive X-ray fluorescence spectrometer. The procedure provided results in satisfactory agreement with inductively coupled plasma spectrometry used as reference method after microwave digestion of the samples in concentrated nitric acid. Statistical tests following extensive regression analyses of the data indicated that interelement effects were not statistically significant and that a simple linear regression was adequate for the calibration of individual metals. 相似文献
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M. Saleem M. Afzal Javed Hanif Riaz Qadeer Imtiaz Hanif 《Journal of Radioanalytical and Nuclear Chemistry》1990,142(2):393-402
An XRF-method for the determination of Sm, Gd, Dy, Er and Eu in uranium solution by use of simple polyethylene bottles has been established. Spectral interferences and matrix effects like absorption enhancement have been rectified using standards of similar composition in the absence of internal standard. Analytical application of the method used has been established on the basis of statistical evaluation. 相似文献
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A. Markowicz N. Haselberger M. Dargie A. Tajani A. Tchantchane V. Valkovic P. R. Danesi 《Journal of Radioanalytical and Nuclear Chemistry》1996,206(2):269-277
A conventional X-ray fluorescence (XRF) method as well as total reflection XRF have been applied to the analysis of various environmental materials. Some methodological changes in order to extend the applicability range and improve the accuracy of the XRF analysis are also discussed. 相似文献
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N. A. Kolpakova A. S. Buinovskii I. A. Mel’nikova 《Journal of Analytical Chemistry》2009,64(2):144-148
A procedure is developed for determining rhenium in gold-containing ores by X-ray fluorescence spectrometry. The adsorption preconcentration of perrhenate ions on activated charcoal is studied. It is found that the pH of the solution, the time of exposing the adsorbent to the solution, UV irradiation, and the presence of associate elements (tungsten, gold, silver, and copper) affect the adsorption. The procedure is applied to the X-ray fluorescence determination of rhenium in gold-containing ores from different deposits. 相似文献
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G. A. Tavares E. Almeida J. G. G. de Oliveira J. A. Bendassolli V. F. Nascimento Filho 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):377-381
This study aimed to evaluate minor and trace elements in the water during different water purification steps of a deionized
water production plant, located at CENA, by total-reflection X-ray fluorescence (TXRF) technique, using Ga as internal standard
for elemental quantification. This approach was capable of determining Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Se, Br, Rb at concentrations
higher than 40–100 μg L−1, and for K, Ca, Sc, Ti, V and Sr at concentrations higher than sub mg L−1 in the water samples. TXRF spectrometer encompasses an X-ray tube with a Mo target with a Zr filter. The elemental characteristic
X-rays were recorded by a Si(Li) semiconductor detector and the X-ray spectra deconvoluted by AXIL software. 相似文献