Direct chemical characterisation of clay suspensions by WD‐XRF

This study was performed to develop a method for directly controlling the chemical composition of clay slurries used in preparing ceramic floor and wall tile bodies by wavelength‐dispersive X‐ray fluorescence (WD‐XRF) spectrometry, without the prior need to dry and prepare the samples as fused beads or pellets for WD‐XRF measurement, owing to the importance of knowing the suspension chemical composition in real time for appropriate control of the industrial process. The study was conducted on a wide range of ceramic floor and wall tile bodies, which are used to prepare different suspensions. The influence of suspension viscosity (from 300 to 7000 cp), of suspension solids content (between 66 and 69%), and of the type of body composition (floor or wall tile) on the WD‐XRF measurement was determined. In these viscosity and solid content ranges, no appreciable differences were observed in the WD‐XRF measurement results, indicating that the possibly arising variations in viscosity and solids content in such clay suspensions in industrial practice do not influence the WD‐XRF measurement. In contrast, the type of body composition did influence the WD‐XRF measurement. The developed method is rapid, reproducible, and accurate, which was verified by analysis of the materials using the customary method of WD‐XRF measurement on fused beads. In addition, this method is cheaper and more harmless to the environment; it minimises waste generation, since no sample preparation is required and the plastic sample holders can be reused, thanks to the reusable sample holder system designed at the Instituto de Tecnología Cerámica laboratories. Copyright © 2011 John Wiley & Sons, Ltd.     

Chemical characterisation by WD‐XRF and XRD of silicon carbide‐based grinding tools

This paper addresses the chemical characterisation of silicon carbide‐based grinding tools. These are among the most widely used grinding tools in the ceramic sector, and instruments are required that enable the grinding tool quality to be controlled, despite the considerable complexity involved in determining grinding tool chemical composition. They contain components of quite different nature, ranging from the silicon carbide abrasive to the resin binder. To develop the analysis method, grinding tools containing silicon carbide with different grain sizes were selected from different tile polishing stages. To develop the grinding tool characterisation method, the different measurement process steps were studied, from sample preparation, in which different milling methods (each appropriate for the relevant type of test) were used, to the optimisation of the determination of grinding tool components by spectroscopic and elemental analyses. For each technique, different particle sizes were used according to their needs. For elemental analysis, a sample below 150 µm was used, while for the rest of the determinations a sample below 60 µm was used. After milling, the crystalline phases were characterised by X‐ray powder diffraction and quantified using the Rietvel method. The different forms of carbon (organic carbon from the resin, inorganic carbon from the carbonates and carbon from the silicon carbide) were analysed using a series of elemental analyses. The other elements (Si, Al, Fe, Ca, Mg, Na, K, Ti, Mn, P and Cl) were determined by wavelength‐dispersive X‐ray fluorescence spectrometry, preparing the sample in the form of pressed pellets and fused beads. The chemical characterisation method developed was validated with mixtures of reference materials, as there are no reference materials of grinding tools available. This method can be used for quality control of silicon carbide‐based grinding tools. Copyright © 2010 John Wiley & Sons, Ltd.     

Quantitative or semi‐quantitative?–laboratory‐based WD‐XRF versus portable ED‐XRF spectrometer: results obtained from measurements on nickel‐base alloys

‘Semi‐quantitative’ analytical procedures are becoming more and more popular. Using such procedures, the question of the accuracy of results arises. The accuracy of an analytical procedure depends to a great extent on spectral resolution, counting statistics and matrix correction. Two ‘semi‐quantitative’ procedures are compared with a quantitative analytical program. Using a laboratory‐based wavelength‐dispersive x‐ray fluorescence (WD‐XRF) spectrometer and a portable energy‐dispersive x‐ray fluorescence (ED‐XRF) spectrometer, 28 different nickel‐base alloy Certified Reference Materials (CRMs) were analyzed. Line interferences and inaccurate matrix correction are reasons for deviations from the reference value. As the comparison shows, ‘semi‐quantitative’ analyses on the WD‐XRF spectrometer can be accepted as quantitative determinations. The investigations show that the results obtained with the portable ED‐XRF spectrometer do not meet the quality requirements of laboratory analysis, but they are good enough for field investigations. Copyright © 2004 John Wiley & Sons, Ltd.     

Distinction and quantification of inorganic sulfur species including thiosulfate by X‐ray fluorescence (WD‐XRF)

Sulfur occurs in a variety of inorganic and organic compounds with oxidation states from ?II up to +VI. Differentiation of these species in solid geochemical samples can be challenging because of oxidation processes during sample preparation by acidic digestion. Applying pressed powder pellets and an analysis by wavelength‐dispersive X‐ray fluorescence minimises reactions with oxidants and water. Main subjects of this work were five inorganic sulfur species, sulfide ?II, elemental sulfur 0, thiosulfate +II, sulfite +IV, and sulfate +VI, and the determination of their fluorescence energies in the sulfur X‐ray spectra. S Kα_1,2 and S Kβ₁ can be observed for all species, S Kβ′ satellites only for species with coordinated oxygen. The results are in good agreement with previously published data. Yet none of the 38 investigated papers from the past 90 years reported S Kα_1,2 of thiosulfate, which was determined as E = 2,309.12 eV in this work apparently for the first time. Binary mixtures of sulfur species are strongly differing in their ability of being quantitatively differentiated, as a reliable quantification requires a sufficient difference of the respective fluorescence energies. Regression equations for each mixture can be used to calculate the ratio of mass fractions of the investigated species from the evaluated fluorescence energy. If boundary conditions are considered, the presented approaches can be applied for analyses of geochemical samples or quality control of technical products. The main advantage of the described methods is the option of implementation to everyday X‐ray fluorescence lab routine without substantial additional effort.     

Intensity correction of WD‐XRF spectra from 2θ to energy

Generally, the energy‐dispersive X‐ray fluorescence spectra are plotted as an equi‐energy interval with the constant energy resolution. On the other hand, the wavelength‐dispersive X‐ray fluorescence spectra are usually measured with an equi‐angle interval supposed the constant angular resolution. When the wavelength axis of wavelength‐dispersive X‐ray fluorescence spectra is converted into energy, the intensity should be also corrected. This intensity correction is important even for a narrow scan range such as Pb Lα and Lβ peaks. The intensity ordering is Lβ > Lα for 2θ plot, but it becomes Lα > Lβ for energy plot. The detailed conversion equations for abscissa and ordinate axes are presented. Copyright © 2012 John Wiley & Sons, Ltd.     

A risk assessment study of heavy metals in ambient air by WD‐XRF spectrometry using aerosol‐generated filter standards

A risk assessment study of the air quality in the surrounding of roads covered with slags coming from the non‐ferrous metal industry was performed. A monitoring campaign was carried out at three locations in Flanders by collecting the PM10 fraction and the total suspended particulates (TSP) of the airborne dust particles, entrapping heavy metals, on membrane filters. The heavy metal concentration on the dust filters was determined by wavelength‐dispersive x‐ray fluorescence (WD‐XRF) spectrometry. The XRF calibration curves were set up with filter standards prepared in the laboratory using an aerosol‐generated loading system. The acquired WD‐XRF results were confirmed by inductively coupled plasma atomic emission spectrometric (ICP‐AES) measurements after acid digestion on a selected number of filters. Electron probe microanalysis (EPMA) confirmed that aerosol‐loaded filter standards and dust filters with a concentration level of the analyzed element below 3300 ng cm^?2 were homogeneously distributed. Dust filters with higher concentrations, and especially filters loaded with the TSP fraction, reflected an inhomogeneous distribution of the analyzed element on the filter. The WD‐XRF analytical results acquired in the monitoring campaign revealed that the concentration of Pb on the dust filters never exceeded the immission standard (yearly average) of 2000 ng m^?3. It can be stated that the impact on human health is limited and can still be reduced by covering the polluted roads with a layer of asphalt. Further evaluation of soil and water samples from the nearby surroundings reveals that the heavy metal content in the slags makes an important contribution to environmental pollution, especially the contamination of groundwater. Copyright © 2003 John Wiley & Sons, Ltd.     

A simple method for quantitative analysis of elements by WD‐XRF using variable dilution factors in fusion bead technique for geologic specimens

A common approach in the quantitative analysis of geological samples by X‐ray fluorescence is to establish calibration lines for elements of interest by using several reference materials (RMs) and/or the combination of RMs and pure chemicals. Herein, we introduce an alternative to use only two RMs, to establish a calibration application. Variation of the dilution factor is employed to generate a dynamic range of concentrations for each RM and to evenly furnish the calibration lines to analyze certain matrices. A wide range of dilution factors were employed from 2–54 times dilution (with respect to the flux to sample ratios). Calibration lines for the major elements including: Si, Al, Ca, Fe, Mg, Na, Mn, and Ti show an extremely high level of linearity with all elements. R² values greater than 0.9990 were obtained for each analyzed element. The calibration application was validated by checking against a variety of geological RMs including petroleum and carbonate rich shale (SGR‐1), Muscovite rich marine shale (SBC‐1), metamorphic rock (SDC‐1), carbonatite (COQ‐1), and types of igneous rocks (GSP‐2, BCR‐2, AGV‐2, QLO‐1, and W‐2). Mixtures of Alumina and Silica (ARG‐1 and ARG‐2) and pure SiO₂ beads were also analyzed to further check the application. Rigorous statistical analysis on the RMs confirms the reliability of the calibration application for the employed matrices. Copyright © 2016 John Wiley & Sons, Ltd.     

Characterization of Indian Ayurvedic herbal medicines for their metal concentrations using WD‐XRF spectrometry

This article describes the details of metal concentrations evaluated using wavelength dispersive X‐ray fluorescence (WD‐XRF) spectrometry. A total of 22 elements, Na, Mg, Al, Si, P, S, K, Ti, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Hg, Pb, Ba, Au, and Sn from 16 Ayurvedic medicines were characterized. The method was validated by analyzing the six certified reference materials of soil standards [NIST SRM‐2710, CRM 027‐050 (US‐EPA certified), PS‐1, TILL‐1 and TILL‐4 (Canadian certified reference material, CCRMP) and JSO‐1 (Japanese certified reference material)]. The elemental concentrations in all the standards are found to be within ± 10% of the reported values. Crystalline phases in the individual drug samples were explained by powder X‐ray diffraction (XRD) technique. Qualitative phase identification was done using the ICDD database. Copyright © 2010 John Wiley & Sons, Ltd.     

Methodology for the determination of minor and trace elements in petroleum cokes by wavelength‐dispersive X‐ray fluorescence (WD‐XRF)

This article describes a methodology for the analysis of minor and trace elements in petroleum cokes by wavelength‐dispersive X‐ray fluorescence (WD‐XRF) spectrometry. The methodology was developed in order to have a rapid and reliable control method of these elements, because they determine coke end uses. There are a number of standard methods of chemical analysis by WD‐XRF or inductively coupled plasma atomic emission spectrometry (ICP‐OES) techniques. However, the standards that use WD‐XRF measurement give detection limits (L_D) above 10 mg·kg^?1 and only analyse a few elements of interest, whereas the ICP‐OES method requires extensive sample handling and long sample preparation times, with the ensuing errors. In order to improve the method described in the standard ASTM D6376 and reach the L_D and quantification limits (L_Q) required, the different stages of the process, ranging from sample preparation to measurement conditions: analytical line, detector, crystal, tube power, use of primary beam filters, and measurement time, were optimised. The samples were prepared in the form of pressed pellets, under conditions of high cleanliness of the mills, crushers, presses, and dies, and of the laboratory itself. The following reference materials were used in measurement calibration and validation: SRM 1632c, SRM 2718, SRM 2719, SRM 2685b, AR 2771, AR 2772, SARM 18, SARM 19, and CLB‐1. In addition, a series of materials were analysed by WD‐XRF and ICP‐OES, and the results were compared. The developed methodology, which uses WD‐XRF, is rapid and accurate, and very low L_D and measurement uncertainties were obtained for the following elements: Al, Ba, Ca, Cr, Cu, Fe, Ge, K, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, and Zn. Copyright © 2010 John Wiley & Sons, Ltd.     

Bead‐releasing agents used in the preparation of solid samples as beads for WD‐XRF measurement

This paper carries the results of an evaluation of various materials, which may be used to aid in the release of a fused bead from its mould during a wavelength‐dispersive x‐ray fluorescence (WD‐XRF) measurement. The following bead‐releasing agents were studied: NaI, LiBr, NH₄I, and LiI. Each was incorporated in different quantities, as a solid and/or in an aqueous solution, together with a flux, into samples of ceramic raw materials. Release agent interference in the WD‐XRF measurement was analysed, and the optimum quantity of release agent needed to obtain suitable beads for WD‐XRF measurement was determined. The best results were obtained for LiI, which yielded reproducible beads without significant interference in the WD‐XRF measurement when a relatively small quantity (0.11 LiI g/bead) was used. Copyright © 2008 John Wiley & Sons, Ltd.     

XRF analysis of arsenic‐doped skin phantoms

Chronic arsenic poisoning can lead to serious health problems including vascular disorders and cancer. Therefore, the development of a system to measure arsenic in vivo would be useful in monitoring exposure. In particular, as skin is one of the tissues in which arsenic has health consequences and is stored for a prolonged period of time, an in vivo measure of skin arsenic content would be a clinically useful measure of chronic exposure. The preliminary development of an x‐ray fluorescence system to measure arsenic in vivo is reported. Standard addition arsenic‐ doped polyester resin phantoms were prepared, and the fluorescence induced by silver K x‐rays from a ¹⁰⁹Cd source was measured. Preliminary estimates of detection limits for an 8 mm thick phantom and an effective dose of ～0.3 µSv are 3.5 ± 0.2 and 10.3 ± 0.5 ppm in 90 and 180° measurement geometries, respectively, for a measurement time of 30 min. Copyright © 2004 John Wiley & Sons, Ltd.     

ED‐XRF set‐up for size‐segregated aerosol samples analysis

The knowledge of size‐segregated elemental concentrations in atmospheric particulate matter (PM) gives a useful contribution to the complete chemical characterisation; this information can be obtained by sampling with multi‐stage cascade impactors. In this work, samples were collected using a low‐pressure 12‐stage Small Deposit Impactor and a 13‐stage rotating Micro Orifice Uniform Deposit Impactor^?. Both impactors collect the aerosol in an inhomogeneous geometry, which needs a special set‐up for X‐ray analysis. This work aims at setting up an energy dispersive X‐ray fluorescence (ED‐XRF) spectrometer to analyse quantitatively size‐segregated samples obtained by these impactors. The analysis of cascade impactor samples by ED‐XRF is not customary; therefore, as additional consistency test some samples were analysed also by particle‐induced X‐ray emission (PIXE), which is more frequently applied to size‐segregated samples characterised by small PM quantities. A very good agreement between ED‐XRF and PIXE results was obtained for all the detected elements in samples collected with both impactors. The good inter‐comparability proves that our methodology is reliable for analysing size‐segregated samples by ED‐XRF technique. The advantage of this approach is that ED‐XRF is cheaper, easier to use, and more widespread than PIXE, thus promoting an intensive use of multi‐stage impactors. Copyright © 2011 John Wiley & Sons, Ltd.     

Nondestructive elemental depth profiling of Japanese lacquerware ‘Tamamushi‐nuri’ by confocal 3D‐XRF analysis in comparison with micro GE‐XRF

We have applied recently two XRF (micro x‐ray fluorescence) methods [micro‐Grazing Exit XRF (GE‐XRF) and confocal 3D‐XRF] to Japanese lacquerware ‘Tamamushi‐nuri.’ A laboratory grazing‐exit XRF (GE‐XRF) instrument was developed in combination with a micro‐XRF setup. A micro x‐ray beam was produced by a single capillary and a pinhole aperture. Elemental x‐ray images (2D images) obtained at different analyzing depths by micro GE‐XRF have been reported. However, it was difficult to directly obtain depth‐selective x‐ray spectra and 2D images. A 3D XRF instrument using two independent polycapillary x‐ray lenses and two x‐ray sources (Cr and Mo targets) was also applied to the same sample. 2D XRF images of a Japanese lacquerware showed specific distributions of elements at the different depths, indicating that ‘Tamamushi‐nuri’ lacquerware has a layered structure. The merits and disadvantages of both the micro GE‐XRF and confocal micro XRF methods are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Depth‐selective elemental imaging of microSD card by confocal micro XRF analysis

A semiconductor device, a microSD card, was measured by using two XRF instruments. 2D elemental images were obtained using a micro‐XRF system with a spatial resolution of 10 µm. Elemental distributions of the near‐surface region of the sample were clearly shown. Titanium was observed in the resin constituting the sample. Nickel and gold were observed on a terminal and localization of the sample. Elemental distribution of copper reflected the circuit structure of the measurement area that was in the neighborhood of the sample surface. Moreover, the elemental depth distributions of the sample were measured by using a confocal micro‐XRF instrument. The confocal micro‐XRF instrument was constructed in the laboratory with fine‐focus polycapillary x‐ray optics. The depth resolution of the developed spectrometer was 13.7 µm at an energy of Au Lβ (11.4 keV). The elemental images obtained at near‐surface by confocal micro‐XRF were the same as the results obtained from 2D micro‐XRF. However, different Cu images were obtained at a depth of several tens of micrometers. This indicates that microSD cards consist of a few different Cu‐circuit structure designs. The elemental depth distributions of each circuit structure of the semiconductor device were clearly shown by confocal micro‐XRF. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of chromium‐containing ceramic pigments by XRF and XRD

As no methodology was found in the literature for characterizing ceramic pigments chemically and mineralogically, the present study was undertaken to establish a methodology for the chemical and phase characterization of ceramic pigments by x‐ray fluorescence (XRF) spectrometry and x‐ray diffraction (XRD). In view of the large number of pigments described in the literature (around 44), the present study was limited to characterizing pigments that contained chromium, which is the most versatile chromophore used in ceramics. Copyright © 2004 John Wiley & Sons, Ltd.     

Precious coral non‐destructive characterization by Raman and XRF spectroscopy

Precious corals are some of the most valuable living marine resources, growing and commercially exploited only in limited areas of the world, namely the Mediterranean Sea and the Northern Pacific Ocean. Their skeleton is formed by calcium carbonate crystallized in the form of calcite whereas their color is because of the presence of partially demethylated polyene pigments. Recently, Pacific corals have been included in the appendix II of CITES list, while Mediterranean corals are still excluded. Different Corallium species of Corallidae family (e.g. Corallium rubrum, Corallium elatius and Corallium secundum) collected from different locations of the Mediterranean Sea and the Pacific Ocean were analyzed by Raman spectroscopy for the characterization of the reddish pigment and by X‐ray fluorescence (XRF) for the determination of the chemical composition of their skeletons, in order to obtain molecular and elemental data with two relatively easy and non‐destructive techniques, which can be used quite steadily for authentication purposes. Raman analysis demonstrated the presence of specific vibrational bands useful to identify the colored pigments as a mixture involving methylated and demethylated polyenes such as carotenoids and parrodienes, characterized by the presence of ―CH₃ groups along the polyene chain. The ratio between the Raman signal and fluorescence background was found to vary as a function of the macroscopic color of the coral, but Raman analyses resulted inadequate for distinguishing between corals having similar color but different origins. On the other side, XRF data provided reliable information for an appropriate separation between Pacific and Mediterranean corals at the elemental level. The results of this study will be of great relevance for the authentication and identification of the origin of corals in trade market by means of completely non‐destructive techniques. Copyright © 2016 John Wiley & Sons, Ltd.     

Quantitative non‐destructive determination of trace elements in archaeological pottery using a portable beam stability‐controlled XRF spectrometer

A portable beam stability‐controlled XRF spectrometer developed at the LNS/INFN laboratories at Catania (Italy) was used for the non‐destructive determination of some trace elements (Rb, Sr, Y, Zr and Nb) in fine pottery artefacts. The XRF system and the method developed to control the energy and intensity stability of the excitation beam are briefly discussed. Concentrations of Rb, Sr, Y, Zr and Nb were determined in 50 fine potsherds from the votive deposit of San Francesco in Catania by using a multi‐linear regression method. Additionally, in order to test the homogeneity of the material composing the fine pottery samples, a small portion of a few potsherds was powdered and analysed using the XRF system and the multilinear regression method. A comparison between non‐destructive and destructive approaches is presented and discussed. Finally, quantitative XRF data were compared with those obtained by chemical analysis of the powdered samples. The results allowed the testing of a non‐destructive methodology to be used for the identification and grouping of the different typological classes of fine pottery mainly represented in the San Francesco sanctuary. Copyright © 2005 John Wiley & Sons, Ltd.     

A modified technique for the preparation of SO2 from sulphates and sulphides for sulphur isotope analyses

A modified technique for the conversion of sulphates and sulphides to SO2 with the mixture of V2O5-SiO2 for sulphur isotopic analyses is described. This technique is more suitable for routine analysis of large number of samples. Modification of the reaction vessel and using manifold inlet system allows to analyse up to 24 samples every day. The modified technique assures the complete yield of SO2, consistent oxygen isotope composition of the SO2 gas and reproducibility of delta34S measurements being within 0.10 per thousand. It is observed, however, oxygen in SO2 produced from sulphides differs in delta18O with respect to that produced from sulphates.     

Validation and traceability of XRF and SEM‐EDS elemental analysis results for solder in high‐reliability applications

A procedure and calibration samples were developed for X‐ray fluorescence spectrometry and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) analysis methods for Sn and Pb amounts in solder and coatings. Test methods are needed by laboratories that perform destructive physical analysis of high‐reliability electronics for MIL‐STD‐1580B. Calibrants are prepared by evaporative deposition of multiple, alternating quantities of pure Sn and pure Pb having mass per unit area proportional to mass fractions of Sn and Pb in a solder being mimicked. Validation reference materials are prepared by evaporative deposition of thin films of SRM 1729 Tin Alloy (97Sn–3Pb). Films are created on high‐purity Ni foil to mimic some actual electronics structures and prevent charging during SEM‐EDS measurements. Maximum thickness of films prepared this way must be kept below approximately 1 µm to ensure that the entire thickness is probed by the primary X‐ray or electron beam and that measured X‐rays come from the entire thickness of all films. Detailed procedures are presented, and method performance was characterized. The primary purpose is to create calibrations for Sn and Pb that are simple to implement and establish traceability to the international system of units. The secondary purpose is to validate calibrations using a certified reference material to prove that, for simpler structures of thin solder coatings on metal, both X‐ray fluorescence and SEM‐EDS provide accurate results. Keeping films thin may be unrealistic in comparison with some, if not many, electronic structures, but this approach enables a laboratory to demonstrate competence in a controlled manner. Copyright © 2014 John Wiley & Sons, Ltd.     

Gilding and pigments of Renaissance marble of Abatellis Palace: non‐invasive investigation by XRF spectrometry

Most of the artworks constituting the collection of Renaissance statuary of Abatellis Palace in Palermo (Sicily) show evidence of colour layers and fragments of gold foil that probably once covered the whole marble surface. The restoration of some of these statues has allowed to carry out archaeometric studies about the painting technique and to highlight the original materials and inclusion present on the precious marbles by two famous Italian sculptors of the Renaissance, Francesco Laurana and Antonello Gagini. The measurements have been performed in situ through the integrated use of two non‐invasive techniques: visible fluorescence stimulated by ultraviolet light and X‐ray fluorescence. The ultraviolet‐induced fluorescence analysis has provided additional information on the conservation status of marble surfaces by differentiating the pictorial materials and highlighting the presence of gilding and pigment traces through their characteristic fluorescence response. The observation in ultraviolet light has been used as valuable guide for the identification of the significant points to be analysed by X‐ray fluorescence to characterise the original materials. X‐ray fluorescence measurements have cast light about their chemical composition and stratigraphical structure. Pictorial layers were identified: vermilion for red layers, blue pigment based on copper for blue layers and pure gold leaf for gilding layers. Principal component analysis of the data was capable of clustering the different painting materials, discriminating through their chemical content. The results represent an important scientific support both to the hypotheses about the original look of the artworks and to the resolution of restoration and conservation questions still open. Copyright © 2012 John Wiley & Sons, Ltd.