Quantitative X-ray Fluorescence Analysis Research Articles

Introducing the BRICC (Bricks and rocks for Instruments’ ceramic calibration) sets: Open-source calibration materials for quantitative X-ray fluorescence analysis

Here we introduce a set of well-characterized historical brick and geological specimens intended to aid the calibration of portable XRF (pXRF) instruments for archaeological ceramics. Known as the BRICC (Bricks and Rocks for Instruments’ Ceramic Calibration) sets, each of the ten matched sets consists of 20 specimens mounted in epoxy discs: 12 bricks and 8 geological specimens to use for calibration. Additionally, a certified reference material – a shale standard measured by 85 labs – is included with each set to assess the resulting accuracy, and a high-purity silica blank is included to check for spectral interferences or other calibration issues. The BRICC sets provide an open-source alternative to pXRF calibration approaches that are proprietary, were devised for oil shales instead of ceramics, and/or rely on expensive and often unavailable certified standards. A set can be tested at Yale or borrowed following loan policies of the Yale Peabody Museum. Publishing all information for the historical bricks and geological specimens – from their origins to the data used to derive the recommended values – fulfills the requirements of scientific transparency. Ultimately, these sets are intended and designed as a means (1) to meet (and exceed) experts’ practices regarding accuracy, reproducibility, and scientific transparency when analyzing ceramics using pXRF and (2) to reduce siloed production of knowledge within established laboratories and, hence, facilitate integration of more diverse perspectives into elemental studies of archaeological ceramics.

Сарнилын пикийг ашигласан тулгуур параметрын арга

Instead of using the complete set of fundamental parameters for solving matrix effects in quantitative energy dispersive x-ray fluorescence analysis, some of them, such as excitation and detection efficiency and dependence of Compton and Reylaeigh scattered intensities on sample composition, were determined from a set of standards such as chemical compounds and pure elements. In this way all fundamental parameters except mass absorbtion coefficients were removed from the calculation procedure, which results in a much simpler formalism. the computer program based on this principle and described in this paper is relatively simple and, can run even on small computers, while the overall error can be kept in the range of few percent.

PolyCO in XRF analysis: Fundamental Parameter Method applied for Japanese Buddhist scroll studies

The quantitative evaluation of chemical elements from X-ray Fluorescence (XRF) analysis still remains a strong hurdle in X-ray Spectrometry, mainly due to significant matrix effects involved in the processes. The Fundamental Parameter Method (FPM) is a valid tool for the calculation of analyte concentration unless the primary source comes from a Synchrotron Radiation facility or the experimental design is based on a confocal layout. The approximation of an infinitely thin sample represents a feasible way to apply the FPM approach along with dedicated X-ray optics implemented in the XRF apparatus to improve the performance of the primary beam (and also of the fluorescence signal reaching the detector). This is routinely available at the XLab Frascati of INFN-LNF thanks to the ”Rainbow X-ray” (RXR) facility, the μXRF station opened to users and optimized for most of X-ray analytical research fields. The basic principle of the station is in the use of various geometrical combinations of polycapillary optics for X-ray beam shaping (focusing/collimation) applied to specially designed laboratory units. The flexible RXR layout allows investigating specimens of the dimensions ranging from several millimeters up to half meter and weighting up to several tens of kilograms with the main advantage of having a detection system able to work separately both at high and low X-ray energies. The aim of the present work is to show the results obtained in quantitative XRF analysis by applying the FPM approach to the RXR experimental layout in a study of the pigments covering two different Japanese scrolls, n.142 838 (also known as Engi Jizo Emakimono) and n. 142 846, coming from the private Ragusa Collection presently stored at Pigorini Museum in Italy.

Preparation of sample solutions using nanoimprint films for quantitative X-ray fluorescence analysis by thin film fundamental parameter method

Various sample preparation methods have been proposed for X-ray fluorescence analysis of mineral components in a liquid. Among them, the dry spot method is widely used; however, the issue is that the prepared dried residue is non-uniform. We developed nanoimprint films using the thermal nanoimprint method. A uniform and thin dry residue was prepared using the nanoimprint film. The thin film fundamental parameter method, a quantitative analysis method used in X-ray fluorescence analysis, was applied to dried residues to analyze their content. As a result, the analysis value was found to be close to the authentication and inductively coupled plasma atomic emission spectromy analysis values.

Evaluation of Quantitative XRF Analysis Applied to Determine Cobalt Sources in Chinese Blue‐and‐White Porcelain

A method using the ratios between MnO, Fe2O3 and CoO to differentiate the cobalt sources for Chinese blue‐and‐white porcelain was developed in Oxford in the 1950s using X‐ray fluorescence (XRF) analysis directly on the glaze. In this paper, six blue‐and‐white porcelain sherds from the Luomaqiao kiln were analysed by XRF on the glaze and by scanning electron microscopy with energy‐dispersive spectrometry (SEM‐EDS) in cross‐section. The ratios between MnO, Fe2O3 and CoO calculated by quantitative XRF and EDS analyses are different. The analysis depths for MnO, Fe2O3 and CoO are < 60 μm by XRF analysis. However, the average glaze thickness of samples is > 400 μm, and the MnO, Fe2O3 and CoO mainly remain in the lower layer of the glaze, which is beyond the analysis depths of XRF analysis. The limitations of major and minor quantitative analyses for differentiating cobalt sources are discussed.

Upcycling of natural volcanic resources for geopolymer: Comparative study on synthesis, reaction mechanism and rheological behavior

The present study prepared geopolymers based on two kinds of volcanic ash, which were mined from Shanxi Province (central China) and Jinlin Province (northeast-China) and denoted as S1 and S2, respectively. The two different volcanic ash were characterized by quantitative X-Ray Diffraction (XRD), X-ray fluorescence (XRF), and particle size analysis. The geopolymer pastes were obtained with the two volcanic ash and 6, 8, and 10 mol/L of sodium hydroxide solution. The mechanical and rheological properties were tested, and the results were correlated with microstructural analysis performed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), Fourier Transform Infrared Spectrometer (FTIR Spectrometer), and 27Al magic angle spinning-nuclear magnetic resonance (27Al MAS-NMR). The results showed that the two kinds of volcanic ash have similar chemical composition while S2 has a higher content of the amorphous phase and smaller median particle size compared with that of S1. S2 has higher geopolymerization activity than S1. The maximum 72-hour compressive strength of the S1 and S2 geopolymer 7.8 MPa and 44.8 MPa, respectively, was acquired when 10 mol/L and 8 mol/L NaOH solution were used. It can be concluded from the results of microscopic experiments that the less content of the amorphous phase, coarser particles, and side reaction between unreacted NaOH and CO2 in the air are the main causes of the lower mechanical strength of S1-based geopolymer. The rheological experiment showed the flow curves of both types of volcanic ash conform to the Bingham model. The yield stress and plastic viscosity coefficient of S2 are higher due to the finer particle size.

Quantitative X-ray fluorescence analysis: Trace level detection of toxic elemental impurities in drug product by ED-XRF spectrometer

Inorganic impurity analysis of pharmaceutical drug products is of paramount importance at trace levels due to the availability of toxic metals. The existing techniques require extensive development and chemical treatment to evaluate the presence of class I (Pb, Cd, Hg and As) and class II (Co, V and Ni) heavy metal elements which are harmful to the environment. To overcome these issues, a cost and time effective wavelength dispersive X-ray fluorescence spectrometry (XRF) was introduced to determine the concentration of trace elements in one of the angiotensin receptor blocker (ARB) (tablet sample 300 mg) according to guidelines addressed in ICH Q3D and USP. The validation study focused on class I and class II elements are also in accordance with regulatory guidelines. Overall it includes the comprehensive characterization of analytical method which is compliant with the requirement of USP. The novelty of this work includes the application of EDXRF in routine analysis of trace elements (especially volatile Hg) present in the pharmaceutical product beyond the previously published studies for the limited number of the non-pharmaceutical regime. Apart from this it also requires minimal sample preparation and method development and is able to quantify toxic impurities which are present in the sample in less than 20 ppm concentration, with the lowest level of detection up to 0.1 ppm.

Validation of secondary fluorescence excitation in quantitative X-ray fluorescence analysis of thin alloy films

Reference-free X-ray fluorescence analysis of multilayered, alloyed thin films in the μm regime with significant secondary fluorescence contributions.

Introducing the Peabody-Yale Reference Obsidians (PYRO) sets: Open-source calibration and evaluation standards for quantitative X-ray fluorescence analysis

A series of well-characterized specimens, known as the Peabody-Yale Reference Obsidians (PYRO) sets, has been designed to aid with calibrating and assessing X-ray fluorescence analysis (XRF) data, including portable XRF (pXRF) measurements, for obsidian sourcing. Each of these ten matched sets consists of 35 specimens: 20 specimens for calibration and 15 specimens for evaluation. These sets include not only obsidians with common geochemical compositions (i.e., alkaline rhyolites) but also rarer ones (i.e., peralkaline rhyolitic, trachytic, and andesitic specimens, including East African Rift obsidians). When used as described, the PYRO sets are suitable to calibrate and evaluate XRF data for obsidians worldwide. A set can be borrowed following loan policies of the Peabody Museum of Natural History, which will also accession a set. Publishing all source information – from their names and GPS coordinates to the datasets used for the recommended values – not only allows the sets to be replicated by others but also fulfills the demands of scientific transparency. Their main purpose is facilitating collaborations and “big data” projects, and the PYRO sets were designed to complement existing protocols for calibration and evaluation. In short, the sets are intended as a tool for almost anyone (e.g., a student who borrows an instrument to source artifacts) to meet – and even exceed – experts' practices involving transparency, accuracy, and reproducibility.

Iterative Monte Carlo procedure for quantitative X-ray fluorescence analysis of copper alloys with a covering layer

Monte Carlo simulations with the MCNP code were applied to evaluation of X-ray fluorescence (XRF) data obtained with two laboratory XRF devices. The aim of this investigation was to test an iterative Monte Carlo procedure used for quantitative analysis of copper alloys which were analyzed alone or they were overlapped with a covering layer. The iterative procedure consists of the performance of several Monte Carlo calculations with varying properties of a simulated object to obtain the best agreement of measured and calculated X-ray count rates of identified elements. The attention was paid to high efficiency of the Monte Carlo simulation to achieve shorter time for computing than for XRF measurements. The robustness of the quantitative MC procedure was tested for situations when the experimental conditions are not known exactly.

Quantitative energy-dispersive X-ray fluorescence analysis for unknown samples using full-spectrum least-squares regression

The full-spectrum least-squares (FSLS) method is introduced to perform quantitative energy-dispersive X-ray fluorescence analysis for unknown solid samples. Based on the conventional least-squares principle, this spectrum evaluation method is able to obtain the background-corrected and interference-free net peaks, which is significant for quantization analyses. A variety of analytical parameters and functions to describe the features of the fluorescence spectra of pure elements are used and established, such as the mass absorption coefficient, the $$G_{i}$$ factor, and fundamental fluorescence formulas. The FSLS iterative program was compiled in the C language. The content of each component should reach the convergence criterion at the end of the calculations. After a basic theory analysis and experimental preparation, 13 national standard soil samples were detected using a spectrometer to test the feasibility of using the algorithm. The results show that the calculated contents of Ti, Fe, Ni, Cu, and Zn have the same changing tendency as the corresponding standard content in the 13 reference samples. Accuracies of 0.35% and 14.03% are obtained, respectively, for Fe and Ti, whose standard concentrations are 8.82% and 0.578%, respectively. However, the calculated results of trace elements (only tens of μg/g) deviate from the standard values. This may be because of measurement accuracy and mutual effects between the elements.

μXRF and LA-ICP-TQMS for quantitative bioimaging of iron in organ samples of a hemochromatosis model

Hereditary hemochromatosis is the most common autosomal recessive genetic disorder of the iron metabolism. Iron accumulation in various organs, especially in liver and pancreas leads to diseases and may cause organ failure. In this study, methods for elemental bioimaging by means of quantitative micro X-ray fluorescence analysis (μXRF) and laser ablation-inductively coupled plasma-triple quadrupole mass spectrometry (LA-ICP-TQMS) were developed and applied to investigate the pathophysiological development of iron accumulation in murine tissue based on animals with an iron-overload phenotype caused by a hepatocyte-specific genetic mutation. The use of an external calibration with matrix-matched gelatin standards enables the quantification of iron by means of μXRF without the typically used fundamental parameters method or Monte Carlo simulation, which becomes more imprecise when analyzing thin tissue sections. A fast, non-destructive screening of the iron concentration and distribution with a spatial resolution of 25 μm in liver samples of iron-overload mice was developed. For improved limits of detection and higher spatial resolution down to 4 μm, LA-ICP-TQMS was used with oxygen as reaction gas. By monitoring the mass shift of 56Fe to 56Fe16O, a limit of detection of 0.5 μg/g was obtained. With this method, liver and pancreas samples of iron-overload mice as well as control mice were successfully analyzed. The high spatial resolution enabled the analysis of the iron distribution in different liver lobules. Compared to the established Prussian blue staining, both developed methods proved to be superior due to the possibility of direct iron quantification in the tissues.

Detailed X-ray diffraction analysis of Ce1-xNdxO2-(x/2) as a surrogate for substoichiometric americium oxide

European Space Agency (ESA) radioisotope power systems will use 241Am as their heat source. The chemical form of the americium oxide has yet to be decided but an option that may be investigated in future research are certain Ia-3 AmO2-(x/2) phases. In a previous investigation, Ia-3 (C-type) Ce1-xNdxO2-(x/2) with x values between 0.5 and 0.7 were proposed as candidate surrogates (Watkinson et al., 2017). A continuous oxalate precipitation and calcination route for fabricating such oxides was presented and the means to target an x value was described (Watkinson et al., 2017). An initial estimate of the lattice parameter was provided in the previous study by fitting Gaussians to X-ray diffraction data peaks. Previous quantitative X-ray fluorescence analysis suggested an x-value of 0.61 had been achieved. Characterising the crystal structure and the oxygen-to-metal ratio, which corresponds to x, of an oxide powder will be essential data for future sintering studies where changes in these parameters will be investigated.In this study, a Rietveld refinement investigation is presented, which has enabled the lattice parameter of the material to be better constrained and estimated more precisely. The result is consistent with the literature; a lattice parameter-x value relationship in the literature was used to estimate the x value using this improved estimate and it confirmed an x value of 0.6 has been made. This investigation has thus further validated the previously presented synthesis method and characterised the crystal structure of the material more precisely in preparation for future sintering trials.

GIMPy: a software for the simulation of X‐ray fluorescence and reflectivity of layered materials

X‐ray fluorescence (XRF) analysis is an established technique for quantitative elemental analysis. Grazing incidence X‐ray fluorescence analysis (GIXRF) extends the application of XRF to thin films because of the improved sensibility. GIXRF shares the phenomenological basis with X‐ray reflectivity, a scattering technique typically used for thin‐film metrology, offering sensitivity to elemental depth. This work presents the GIMPy (Grazing Incidence Material analysis with Python) software developed for the analysis of GIXRF spectra by combining a fundamental parameter approach to quantitative XRF analysis and the electric field calculation in stratified media, which also delivers the total reflected intensity as measured in X‐ray reflectivity experiments. An XRF experiment can be modelled from the source, modulation of the primary beam, interactions with a layered sample, absorption of the emitted fluorescence intensities, and the response function of semiconductor energy dispersive detectors obtaining a simulation of the expected spectrum that can be directly compared with the acquired one. The fundamental parameter part includes signal enhancements by cascade effect and secondary fluorescence. The code offers the possibility to take into account the effects originated by deviations from ideal conditions: non‐monochromatic excitation, beam divergence, beam size and shape, sample‐inspected area, and solid angle of detection. The functionality of the code is demonstrated on a set of semiconductor substrates (Si, Ge, and GaAs) and shallow dopant distributions of arsenic in silicon. Copyright © 2017 John Wiley & Sons, Ltd.

Use of models of secondary X-ray fluorescence spectra to determine the measurement conditions in X-ray spectral methods of material analysis

The principles of construction and the components of a model of X-ray fluorescence signal generation are considered in this paper. It is shown that the developed model describes the X-ray spectra of various materials rather well. Issues with choosing the optimal parameters of measurements in the quantitative X-ray fluorescence analysis of individual samples using the constructed models are discussed.

Unified Theory for Decoding the Signals from X-Ray Florescence and X-Ray Diffraction of Mixtures.

For research and development or for solving technical problems, we often need to know the chemical composition of an unknown mixture, which is coded and stored in the signals of its X-ray fluorescence (XRF) and X-ray diffraction (XRD). X-ray fluorescence gives chemical elements, whereas XRD gives chemical compounds. The major problem in XRF and XRD analyses is the complex matrix effect. The conventional technique to deal with the matrix effect is to construct empirical calibration lines with standards for each element or compound sought, which is tedious and time-consuming. A unified theory of quantitative XRF analysis is presented here. The idea is to cancel the matrix effect mathematically. It turns out that the decoding equation for quantitative XRF analysis is identical to that for quantitative XRD analysis although the physics of XRD and XRF are fundamentally different. The XRD work has been published and practiced worldwide. The unified theory derives a new intensity-concentration equation of XRF, which is free from the matrix effect and valid for a wide range of concentrations. The linear decoding equation establishes a constant slope for each element sought, hence eliminating the work on calibration lines. The simple linear decoding equation has been verified by 18 experiments.

Compositional Changes of CuxAu upon Dealloying below the Critical Potential

X-ray reflectivity and spectroscopy, voltammetry, and scanning probe microscopy were used to investigate the dealloying of CuxAu (with x ≈ 4) below the critical potential. We studied ultrathin films deposited on oxidized silicon wafers with a thickness of 2.2, 8.5, and 43 nm, which had been determined precisely by X-ray reflectivity. With the help of quantitative X-ray fluorescence (XRF) analysis, the average composition of the films before and after the leaching was determined. In this way, the amount of material going into solution could precisely be analyzed. A compositional depth profile was obtained by angle-dependent hard X-ray photoelectron spectroscopy before and after the dealloying. Two novel findings are reported. (1) Close to the Cu/Cu2+ redox potential, a pronounced increase in current is observed in the voltammogram. While this charge transfer seems to indicate the dissolution of Cu2+, XRF analysis proves that no copper has been lost to the solution. (2) The XRF analysis shows that some gold...

Traceable Quantitative Raman Microscopy and X-ray Fluorescence Analysis as Nondestructive Methods for the Characterization of Cu(In,Ga)Se2 Absorber Films.

The traceability of measured quantities is an essential condition when linking process control parameters to guaranteed physical properties of a product. Using Raman spectroscopy as an analytical tool for monitoring the production of Cu(In1-xGax)Se2 thin-film solar cells, proper calibration with regard to chemical composition and lateral dimensions is a key prerequisite. This study shows how the multiple requirements of calibration in Raman microscopy might be addressed. The surface elemental composition as well as the integral elemental composition of the samples is traced back by reference-free X-ray fluorescence analysis. Reference Raman spectra are then generated for the relevant Cu(In1-xGax)Se2 related compounds. The lateral dimensions are calibrated with the help of a novel dimensional standard whose regular structures have been traced back to the International System of Units by metrological scanning force microscopy. On this basis, an approach for the quantitative determination of surface coverage values from lateral Raman mappings is developed together with a complete uncertainty budget. Raman and X-ray spectrometry have here been proven as complementary nondestructive methods combining surface sensitivity and in-depth information on elemental and species distribution for the reliable quality control of Cu(In1-xGax)Se2 absorbers and Cu(In1-xGax)3Se5 surface layer formation.

Understanding metal homeostasis in primary cultured neurons. Studies using single neuron subcellular and quantitative metallomics.

The purpose of this study was to demonstrate how single cell quantitative and subcellular metallomics inform us about both the spatial distribution and cellular mechanisms of metal buffering and homeostasis in primary cultured neurons from embryonic rat brain, which are often used as models of human disease involving metal dyshomeostasis. The present studies utilized synchrotron radiation X-ray fluorescence (SRXRF) and focused primarily on zinc and iron, two abundant metals in neurons that have been implicated in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Total single cell contents for calcium, iron, zinc, copper, manganese, and nickel were determined. Resting steady state zinc showed a diffuse distribution in both soma and processes, best defined by the mass profile of the neuron with an enrichment in the nucleus compared with the cytoplasm. Zinc buffering and homeostasis was studied using two modes of cellular zinc loading - transporter and ionophore (pyrithione) mediated. Single neuron zinc contents were shown to statistically significantly increase by either loading method - ionophore: 160 million to 7 billion; transporter 160 million to 280 million atoms per neuronal soma. The newly acquired and buffered zinc still showed a diffuse distribution. Soma and processes have about equal abilities to take up zinc via transporter mediated pathways. Copper levels are distributed diffusely as well, but are relatively higher in the processes relative to zinc levels. Prior studies have observed iron puncta in certain cell types, but others have not. In the present study, iron puncta were characterized in several primary neuronal types. The results show that iron puncta could be found in all neuronal types studied and can account for up to 50% of the total steady state content of iron in neuronal soma. Although other metals can be present in iron puncta, they are predominantly iron containing and do not appear to be associated with ferritin cages or transferrin receptor endosomes. The iron content and its distribution in puncta were similar in all neuron types studied including primary dopaminergic neurons. In summary, quantitative measurements of steady state metal levels in single primary cultured neurons made possible by SRXRF analyses provide unique information on the relative levels of each metal in neuronal soma and processes, subcellular location of zinc loads, and have confirmed and extended the characterization of heretofore poorly understood cytoplasmic iron puncta.

Quantitative X-ray Fluorescence Analysis of Biomass (Switchgrass, Corn Stover, Eucalyptus, Beech, and Pine Wood) with a Typical Commercial Multi-Element Method on a WD-XRF Spectrometer

Quick and reliable inorganic elemental chemical analysis of biomass (including solid biofuels) is of importance in the increasing utilization and trade of biomass. In particular, it is important for the exploitation of contaminated/dirty biomass/biomass waste, and potentially also as a tool in ascertaining the type/origin of biomass. X-ray fluorescence (XRF) spectrometry performed directly on the raw biomass with limited prior sample preparation is an attractive method for performing such inorganic elemental analysis. In the present study, we therefore carefully investigate the performance of a commercial multi-element standardless XRF method by analyzing five common biomass types (switchgrass, corn stover, eucalyptus, beech, and pine wood). Sample preparation involves milling the raw biomass using cutter and rotor mills (avoiding ball-milling) and cold-pressing the powdered samples into pellets using wax binder. XRF users often rely on this type of commercial precalibrated or ‘standardless’ methods delivered with their XRF spectrometer. However, these methods are often sold without any guarantee on performance. We recently demonstrated the quite good performance of a typical commercial precalibrated/standardless method when analyzing biomass in the ideal form of certified reference material. In the present article, we report now on analysis of common raw biomass using the same method purchased with a 4 kW wavelength dispersive (WD) XRF spectrometer. The accuracy (trueness and precision) is determined by comparing the XRF data with the elemental composition obtained by standard elemental analysis (ICP-OES and ion-chromatography). The elements positively detected by the XRF are Na, Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Sr, and maybe Mo. For elements above 25 ppm, the XRF data show a relative systematic error (bias, trueness) typically better than ±15% independent of the concentration. The elements present with >1000 ppm (Mg, Si, Cl, K, Ca) consistently show a positive bias of 3–18% relative. The relative precision (measured as the relative standard error) is better than ±5% (typically ±1%) for concentrations >25 ppm (obtained with 10–30 measurements). Quantifying elements below 25 ppm (Co, Ni, Cu, Zn, Sr, Mo) is possible in some cases, but it requires a more detailed study for each specific element. For example, Cu can be determined down to a few parts per million with an appropriate correction for the method bias. Occasionally, larger relative biases of up to 45–90% can occur for certain elements (Cl, Si) in certain samples, so care should be taken to carefully test the applied method for the particular samples and elements of interest. Quantification of silicon (Si) by XRF works well for concentrations >100 ppm. The XRF method can further be used to estimate the ash yield from biomass combustion with a relative bias better than ±10%. It is shown that the errors on the elemental composition are dominated by systematic errors (biases), and therefore, measuring the two sides of a single pellet combined with correction for any bias is the optimum approach. The five biomass types employed here, combined with the 13 certified reference materials employed in our previous study, span a broad range of biomass types with the XRF method generally producing reliable results (keeping in mind the limitations and needed bias corrections) with errors comparable to the standard reference methods. This suggests that typical standardless/precalibrated XRF methods work well in elemental analysis of raw biomass (keeping in mind the limitations) and therefore could be considered for general usage in, for example, industrial analytical laboratories requiring fast elemental analysis of biomass.