Estimation studies of strontium in simulated nuclear waste solutions by WDXRF

Estimation of strontium has been studied by wavelength dispersive X-ray fluorescence spectrometery (WDXRF) as an analytical technique using Sr K as an analytical line. Lower limits of detection, precision, and intensities were plotted against counting time and concentrations to assess optimum time for measurement, expected scatter of the results, and calibration curves for intensity to concentration relationship. For its assessment the best equations determined by regression and least squares fitting along with a standard multiple addition technique were applied to a complex fuel admixture and simulated nuclear fuel solutions at a bum up of 650 GJ/Kg after a 0.5-year cooling time.     

Characterization of “oil on copper” paintings by energy dispersive X-ray fluorescence spectrometry

Energy dispersive X-ray fluorescence is a common analytical tool for layer thickness measurements in quality control processes in the coating industry, but there are scarce microanalytical applications in order to ascertain semi-quantitative or quantitative information of painted layers. “Oil on copper” painting becomes a suitable material to be analysed by means of X-ray fluorescence spectrometry, due to the metallic nature of substrate and the possibility of applying layered models as used in coating industry. The aim of this work is to study the suitability of a quantitative energy dispersive X-ray fluorescence methodology for the assessment of the areal distribution of pigments and the characterization of painting methods on such kind of pictorial artworks. The method was calibrated using standard reference materials: dried droplets of monoelemental standard solutions laid on a metallic plate of copper. As an example of application, we estimated pigment mass distribution of two “oil on copper” paintings from the sixteenth and eighteenth centuries. Pictorial layers have been complementarily analysed by X-ray diffraction. Apart of the supporting media made of copper or brass, we could identify two different superimposed layers: (a) a preparation layer mainly composed by white lead and (b) the pictorial layer of variable composition depending on the pigments used by the artist on small areas of the painting surface. The areal mass distribution of the different elements identified in the painting pigments (Ca, Cr, Mn, Fe, Zn, Cd, Hg and Pb) have been determined by elemental mapping of some parts of the artworks.     

Determination of Rb and Sr concentrations in rocks by radioisotope X-ray fluorescence analysis

A method is described for Rb and Sr concentration determinations in rocks by radioisotope X-ray fluorescence analysis. The yield/concentration ratios were established by increasing the concentrations of the examined elements in the sample and recording each spectrum. The analytical error in the 100-1,000 ppm concentration range was 2–4%, and for 50 ppm about 10%, and the detection limit was 5–10 ppm.     

The Observation of Strong Absorption of the Yttrium Lα Line in Sialon Ceramics

 β-sialon ceramics sintered with yttria additives have been studied with the use of an electron probe X-ray analysis (EPMA). Sialon ceramics were prepared from a carbothermally derived β-sialon powder and then sintered in a nitrogen atmosphere with yttria admixture. The above process was followed by annealing in flowing nitrogen. Scanning electron microscope (SEM) observations have shown that the sintered material contains a glassy phase (Y-Si-Al-O-N) on the grain boundaries. X-ray diffraction (XRD) after annealing in nitrogen revealed the presence of a considerable amount of yttrium aluminium garnet (YAG). The higher voltage of 30 kV was used in order to excite the yttrium K_α radiation (14.96 keV) at an appropriate overvoltage ratio because in some phases of the material, the disappearance of the yttrium L_α line has been observed during EPMA examination at an accelerating voltage of 15 kV in energy dispersive spectra (EDS). The intensity of the yttrium K_α line was sufficiently high, while the Y L_α line was not seen in the ED spectrum. Because the position of the yttrium L_α line (1.922 keV) is very close to the Si (K) absorption edge (1.84 keV), the strong absorption at this edge is probably responsible for the effect. This result should be considered as a serious warning in the case of EPMA (EDS) studies on compounds or mixtures suspected to contain both silicon and yttrium, because at electrons energies lower than 15 keV, the presence of yttrium in materials can go unnoticed. In wavelength dispersive spectra (WDS) obtained at 15 keV the intensity of the yttrium L_α line was also very low but measurable.     

Study on the retention of uranyl ions on modified clays with titanium oxide

Four analytical techniques—instrumental neutron activation analysis (INAA), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscope energy dispersive X-ray fluorescence (SEM-EDXRF), and proton induced X-ray emission (PIXE)—were evaluated in the context of air pollution biomonitoring studies. Three combinations INAA/ICP-MS, ICP-MS/PIXE and ICP-MS/SEM-EDXRF are illustrated by experimental results.     

Design Features of a High Resolution Microcalorimeter EDX System

 High resolution, superconducting detectors allow energy dispersive X-ray spectrometry (EDX) with energy resolution and energy threshold far beyond the levels obtained with semiconductor detectors. These cryogenic detectors are run at temperatures of less than 100 mK and combine the excellent energy resolution of wavelength dispersive X-ray spectrometry (WDX) with the fast, energy dispersive analysis of EDX. CSP cryogenic spectrometer’s microcalorimeter type EDX cryodetectors are equipped with a mechanical cooling system that runs vibration free and allows completely automated operations on scanning electron microscopes (SEMs), field emission guns (FEGs) and transmission electron microscopes (TEMs). This detector type offers new opportunities in material analysis, especially when low excitation energies are applied or light elements are to be determined.     

Application of energy dispersive X-ray fluorescence for the determination of metallic impurities in ThO<Subscript>2</Subscript>

Energy dispersive X-ray fluorescence (EDXRF) spectrometric methods have been developed for the determination of some common metallic impurities in ThO₂ matrix. A series of ThO₂ standards containing the analyte impurities in the range 10–100 (or 100–500) μg/g was prepared synthetically. The spectrometer conditions were optimized to obtain calibration plots for the various analytes. The accuracy and precision of the developed methodology for regular assay of ThO₂ was evaluated by analyzing three synthetic samples. Further three secondary ThO₂ standards were analyzed by EDRXF to check the developed methods. The determined concentrations of Ca, Cr, Fe, Ni and Cu were in good agreement with the certified values of the secondary standards.     

Separation and determination of selenium in water samples by the combination of APDC coprecipitation: X-ray fluorescence spectrometry

A sensitive and non chromatographic analytical procedure for the separation of inorganic selenium species in natural water has been performed. A combination of APDC coprecipitation and determination by an absolute thin layer Energy dispersive X-ray fluorescence spectrometry method was used. The influence of various analytical parameters such as element concentration, oxidation states and pH on the recoveries of Se (IV) was examined. The presence of organic matter and bicarbonate anions, typical components in Cuban groundwater samples, was also tested. Negligible matrix effects were observed. At pH 4 a 100% recovery was found for Se (IV). The coprecipitation recovery of the oxidized selenium species (Se (VI)) was null for the selected concentration range (5–100 μg L⁻¹). When the Se (VI) was reduced by heating the solution with 4 mol L⁻¹ HCl, quantitative recovery was also obtained. The determination of total selenium was conducted by the application of the oxidation–reduction process and the analytical procedure for Se (IV). Se (VI) content was calculated as the difference between total selenium and Se (IV). The detection limit was 0.13 μg L⁻¹. The relative standard deviation was lower than 3.5% for 5 μg L⁻¹ of Se (IV). The trueness of the method was verified by using standardized hydride generation-atomic absorption spectrometry technique. The results obtained using the EDXRF technique were in good agreement with the ones determined by HG-AAS. The proposed method was applied to the determination of Se (IV) in surface water and groundwater samples.     

Elemental Analysis of Cement by Calibration-Free Laser Induced Breakdown Spectroscopy (CF-LIBS) and Comparison with Laser Ablation – Time-of-Flight – Mass Spectrometry (LA-TOF-MS), Energy Dispersive X-Ray Spectrometry (EDX), X-Ray Fluorescence Spectroscopy (XRF), and Proton Induced X-Ray Emission Spectrometry (PIXE)

The purpose of the present study is to determine the elemental composition of Pakistani cement brands using calibration-free laser induced breakdown spectroscopy (CF-LIBS) and to compare the obtained results with the other analytical techniques such as, laser ablation – time-of-flight – mass spectrometry (LA-TOF-MS), energy dispersive X-ray spectrometry (EDX), X-ray fluorescence spectroscopy (XRF) and proton induced X-ray emission spectrometry (PIXE). Compositional results reveal that all the cement brands are mainly composed of calcium, silicon, iron, aluminum, magnesium, potassium, sodium, titanium, lithium and strontium with varying concentrations. The compositions obtained by LIBS and LA-TOF-MS are in good agreement with results obtained by the other standard techniques and demonstrate the potential use of LIBS for the online monitoring of industrial cement production.     

Chemical and mineralogical characterization on glazes of ceramics from Coimbra (Portugal) from the sixteenth to nineteenth centuries

Chemical, mineralogical and textural characterizations were performed on glazed pieces prepared in laboratory as well as on faiences fragments collected from the existing remains in “Santa Clara-a-Velha” monastery (Coimbra, Portugal). The chemical investigation was carried out using micro X-ray fluorescence (μ-EDXRF) and wavelength dispersive X-ray fluorescence (WDXRF); the mineralogical results using X-ray diffraction (XRD) and the textural profile was obtained by scanning electron microscopy coupled with an energy dispersive spectroscopy system (SEM-EDS). Attention has been drawn to the glaze mineralogical changes during the firing temperature process, where three different types of glazes were submitted to three different firing temperatures (800 °C, 900 °C and 1,000 °C). Under these conditions, it is possible to relate the mineralogical content of the fragments to their firing temperature. Furthermore, we focused our purposes on identifying the technological aspects of the ceramic production in Coimbra, such as the raw materials, manufacture techniques and firing temperature adopted for the glaze. The latter aspect is highly dependent on the ceramic materials. In the framework of a more general project, this survey has as premise the recognition of a pattern, which is thought to be exclusively typical from the region of Coimbra. The perspective developed in the present work is towards reliable archaeometric criteria, which can be used to characterise scientifically the ceramics from Coimbra.     

Electron Probe Microanalysis of Nitrogen in Glasses and Glass Ceramics

 A homogeneous (phosphate glass) and a heterogeneous (glass ceramic) material were chosen to develop a method for electron microprobe analysis of nitrogen in glasses and glass ceramics. The metaphosphate (50 mole-% P₂O₅, 25 mole-% BaO, 25 mole-% Rb₂O) base glass and the silicate glass (composition of the base glass: 6.9 mole-% Al₂O₃, 21.3 mole-% MgO, 47.3 mole-% SiO₂, 5.1 mole-% CaO, 19.4 mole-% AlN) were melted and cooled down to room temperature. In a second step, the two materials were nitrided by applying dry NH₃ in a special tube furnace. Up to 5 wt.-% of nitrogen could be introduced. The ability of energy dispersive (EDX) as well as wavelength dispersive (WDX) electron probe microanalysis to analyze low contents of light elements in combination with highly concentrated heavy elements was tested both for glasses and for glass ceramics. Measuring conditions had to be optimized to get reliable analytical results as well as to avoid radiation damage of the glasses which may occur especially in the case of wavelength dispersive X-ray analysis. The results were compared with two different analytical methods: inductive coupled plasma analysis and a commercial nitrogen-oxygen-analyzer (the specimen is decomposed by heating and the released gases are analyzed spectroscopically (O) and electrically (N)).     

Energy dispersive X-Ray fluorescence determination of thorium in phosphoric acid solutions

Energy dispersive X-ray fluorescence studies on determination of thorium (in the range of 7 to 137 mg/mL) in phosphoric acid solutions obtained by dissolution of thoria in autoclave were made. Fixed amounts of Y internal standard solutions, after dilution with equal amount of phosphoric acid, were added to the calibration as well as sample solutions. Solution aliquots of approximately 2–5 µL were deposited on thick absorbent sheets to absorb the solutions and the sheets were presented for energy dispersive X-ray fluorescence measurements. A calibration plot was made between intensity ratios (Th Lα/Y Kα) against respective amounts of thorium in the calibration solutions. Thorium amounts in phosphoric acid samples were determined using their energy dispersive X-ray fluorescence spectra and the above calibration plot. The energy dispersive X-ray fluorescence results, thus obtained, were compared with the corresponding gamma ray spectrometry results and were found to be within average deviation of 2.6% from the respective gamma ray spectrometry values. The average precision obtained in energy dispersive X-ray fluorescence determinations was found to be 4% (1σ). The energy dispersive X-ray fluorescence method has an advantage over gamma ray spectrometry for thorium determination as the amount of sample required and measurement time is far less compared to that required in gamma ray spectrometry.     

Quantitative analysis of sea-bed sediments from Eastern Black Sea by EDXRF spectrometry

Sea-bed sediments from Eastern Black Sea have been analyzed for their Fe, Ba and Sr contents using the methods of standard addition and energy dispersive X-ray fluorescence (EDXRF). Samples were prepared from powder sifted by a 200 mesh sieve. An annular 100 mCi²⁴¹Am radioactive source emitting 59.543 keV photons was used for excitation and a Ge(Li) detector, which has a 190 eV FWHM for 5.9 keV photons was used for intensity measurements. 2048 channels of the MCA are employed for 20 or 30 min. Dried and ground sea-bed sediments are found to contain 2.95–7.50% Fe, 0.032–0.268% Ba and about 73–273 ppm Sr. These results agree with those obtained via atomic absorption methods.     

粉末压片-X射线荧光光谱法快速测定生石灰粉中氧化钙和二氧化硅

采用粉末压片法制样,建立了波长色散X射线荧光光谱法快速测定生石灰粉中氧化钙、二氧化硅的分析方法。由于没有国家标准样品,采用自制生石灰粉标准样品绘制工作曲线。考察了样品粒度及吸潮对分析结果的影响。实验表明,在样品粒度为74μm、压样机压力为12 MPa、压制时间为45s的制样条件下荧光计数率最稳定,在30min内测定样品效果最佳。采用α理论系数法和经验系数法相结合校正基体影响。对同一生石灰粉样品进行精密度实验,各组分的相对标准偏差(RSD,n=11)在0.04%~0.43%。测定了5个生石灰粉样品,所得结果与常规化学分析方法测定值相符。     

Study on the interaction between diphenhydramine and erythrosin by absorption,fluorescence and resonance Rayleigh scattering spectra

In pH 4.5 Britton-Robinson(BR)buffer solution,erythrosin(ET)can react with diphenhydramine(DP)to form a 1:1 ion-association complex,which not only results in the change of the absorption spectra,but also results in the great enhancement of resonance Rayleigh scattering(RRS)and the quenching of fluorescence.Furthermore,a new RRS spectrum will appear,and the maximum RRS wavelength was located at about 580 nm.In this work,the spectral characteristics of the absorption,fluorescence and RRS,the optimum conditions of the reaction and the properties of an analytical chemistry were inves- tigated.A sensitive,simple and new method for the determination of DP by using erythrosin as a probe has been developed.The detection limits for DP were 0.0020μg/mL for RRS method,0.088μg/mL for absorption method and 0.094μg/mL for fluorophotometry.There was a linear relationship between the absorbance,RRS and fluorescence intensities and the drug concentration in the range of 0.0067-2.0, 0.29-6.4 and 0.31-3.2μg/mL,respectively.The effects of the interaction of diphenhydramine and erythrosin on the absorption,fluorescence and resonance Rayleigh scattering spectra were discussed. In light polarization experiment,the polarization of RRS at maximum wavelength was measured to be P =0.9779,and it revealed that the RRS spectrum of DP-ET complex consists mostly of resonance scat- tering and few resonance fluorescence.In this study,enthalpy of formation and mean polarizability were calculated by AM1 quantum chemistry method.In addition,the reaction mechanism and the rea- sons for the enhancement of scattering spectra and the energy transfer between absorption,fluores- cence and RRS were discussed.     

A method for prompt in situ uranium assay and free acidity determination in uranyl nitrate solutions by density and Raman measurements

A precise and accurate compositional characterization methodology using wavelength dispersive X-ray fluorescence (WDXRF) spectrometry for mixed oxide nuclear fuels is reported. The methodology involves pelletization of standards and samples. The calibration plots were made by plotting the percent intensity of analyte X-ray lines against their amount percent. The relative standard deviation were 0.4% and 0.25%, respectively for uranium and thorium, having U ranging from 2.85 to 4.2 (wt%). The analytical results were compared with chemical analysis method and were in good agreement. The developed WDXRF method is non-destructive, fast and better in comparison to chemical analysis methods.

     

Two radiometric methods for the fast determination of calcium in cement raw mix

Fast determination of calcium in cement raw mix is a very important problem from the economic point of view. In order to solve this task, the following two methods are proposed: (i) Non-dispersive X-ray fluorescence analysis (using¹⁰⁹Cd as a source of primary radiation); (ii) back-scattering of β-particles (using⁹⁰Sr+⁹⁰Y as a source). The influence of the following factors has been studied in both methods: (i) concentration of iron in the matrix; (ii) water content; (iii) grain size of the sample. The influence of the energy of the primary radiation on the slope of a calibration curve has been analyzed in the fluorescence method. In the concentration range of 42–52% CaO, the absolute standard error is 0.17% CaO in the fluorescence analysis, and 0.5% CaO for the method of back-scattering of β-particles. The average time of a determination is about 2 min.     

X射线荧光光谱法测定石化产品中的总氯

采用能量色散X射线荧光光谱法测定石化产品中的总氯含量。采用钛靶X射线管及高分辨率硅漂移半导体检测器,在管电压10 kV、管电流0.3 mA的最佳实验条件下,氯含量在30~1 000 mg/L范围内与荧光强度呈良好的线性关系,相关系数大于0.999,检出限为6.24 mg/kg。利用该法对90#石油醚、120#溶剂油、润滑油、基础油等中的氯含量进行测试,测定结果与GB/T 18612–2011方法相一致。该方法可以作为测定石化产品总氯含量的新的试验方法。     

The stained glass window of the southern transept of St. Anthony's Basilica (Padova, Italy): study of glasses and grisaille paint layers

This work reports results from a chemico-physical study of the stained glass window of the southern transept of St. Anthony's Basilica (Padova, Italy), dated to the late 19th century AD. Selected samples of glass with or without grisailles were characterised by means of various X-ray spectrometric techniques, such as wavelength dispersive X-ray fluorescence, electron microprobe, and scanning electron microscopy with energy dispersive X-ray microanalysis, coupled, in some cases, with X-ray powder diffraction. Integration of analytical results revealed many types of glass related to different phases of the “life” of stained glass, and the production technology of grisailles. In addition, the degree of damage undergone throughout the last century due to materials used in the production of windows was studied, to design and optimise a combined conservation and restoration strategy. Lastly, another important aim of the present study was to amplify the database on 19th-century stained glass windows, little documented in the literature.     

Improved method for the separation of radioactive strontium from various samples by mixed solvent anion exchange

Procedures for the separation and determination of⁹⁰Sr in liquid samples, with cation and anion exchangers have been described. Strontium, yttrium and other cations bind to the cation exchanger and are eluted from the column by means of nitric acid. Separation of yttrium and strontium from other cations is carried out on columns filled with strong base anion exchangers in nitrate form with alcoholic solutions of nitric acid. This separation method enables the determination of⁹⁰Sr through yttrium on a low-level gas flow α, β-counter, as well as through strontium on a lowlevel liquid scintillation counter by means of Cherenkov counting. Such procedures have been tested by the determination of⁹⁰Sr in water, wine, medium radioactive liquid waste samples, milk and clover samples. For comparison, the determination has also been carried out by the standard method. It has been showed that the developed procedures might produce a high efficiency in strontium separation and a satisfactory accuracy of determination.