Wavelength Dispersive X-ray Fluorescence Spectrometry Research Articles

The use of wavelength dispersive X-ray fluorescence and discriminant analysis in the identification of the elemental composition of cumin samples and the determination of the country of origin

Sixteen elements found in 33 cumin spice samples from China, India, Syria, and Turkey were analysed by wavelength dispersive X-ray fluorescence (WDXRF) spectroscopy using the commercially available Bruker – AXS S4 Explorer for the purpose of using the elements to discriminate among country of origin. Pellets were prepared of the samples and elemental concentrations calculated from calibration curves constructed using four National Institute of Standards and Technology (NIST) standards. A separate NIST tomato standard (1573a) was used as a validation check, while the WDXRF data for six of the cumin samples was further validated using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The elements measured included Ca, Mg, K, P, S, Al, Ba, Br, Cl, Fe, Na, Mn, Rb, Sr, Cu, and Zn and were detected in the range from an average mean of 4.3mgkg−1 for Ba up to 19223.8mgkg−1 for K. Analysis of variance (ANOVA) was used to determine which elemental concentrations were statistically different from one another, and discriminant analysis was used to classify the cumin samples by country of origin. Using only eight elements (Ca, Mg, K, Fe, Na, Mn, Sr, and Zn) we were able to differentiate among cumin samples from four different geographic origins. Validation of the model with the validation set yielded 87.50% accuracy. Successful discrimination with just eight elements will allow for higher throughput in the screening of cumin samples using WDXRF for origin verification in less time.

Effect of solidification parameters on the microstructure of directionally solidified Sn-Bi-Zn lead-free solder

Sn-Bi-Zn lead free solder alloy was directionally solidified upward at a constant temperature gradient (G=3.99 K/mm) with a wide range of growth rates (8.3–478.6 μm/s) and at a constant growth rate (V=8.3 μm/s) with a wide range of temperature gradients (1.78–3.99 K/mm) using a Bridgman type directional solidification furnace. Wavelength-Dispersive X-ray Fluorescence spectrometry and X-ray diffraction were used to identify the compositions and phases in the microstructure. Dependence of eutectic spacings (λ) on the growth rate (V), temperature gradient (G) and cooling rate (Ṫ) were determined using linear regression analysis. From the experimental results, it can be concluded that the values of λ decrease with the increasing the values of V, G and Ṫ. The value of λ2V was determined using the measured values of λ and V. The results obtained in the present work have been compared with previous results obtained for binary or ternary alloys.

Geostatistical analyses and fractionation of heavy metals in urban soil from industrial district in Weinan, NW China

The concentrations of metals (Pb, Cr, Ba, Zn, V, Mn, Co, Cu, Ni and As) in 38 soil samples collected from the industrial district in Weinan (NW China) were determined by wavelength dispersive X-ray fluorescence spectrometry. The magnetic parameters of soil including low-/high-frequency susceptibility and frequency-dependent susceptibility were measured. The modified three-step BCR sequential extraction procedure was used to evaluate mobility, availability and persistence of trace elements in urban soil samples. Multivariate (principal component analysis, clustering analysis and correlation analysis) and geostatistical analysis (ArcGIS tools) were applied to the obtained data to evaluate the analytical results and to identify the possible pollution sources of metals as well as geo-spatial distributions. The results revealed that the sampling area was mainly influenced by two main sources: (1) Ba, Cu, Pb, Cr and Zn were mainly derived from industrial sources, which combined with coal combustion as well as traffic factor. The mobility sequence based on the sum of the BCR sequential extraction stages was: Pb (53.79 %) > Zn (51.78 %) > Cu (50.96 %) > Ba (42.59 %) > Cr (18.47 %). Pb was the metal predominantly associated (~46.86 %) with the form bound to Fe/Mn oxides, and the highest percentage of Zn was exchangeable and carbonate-bound fraction. Cu was present mainly in organic fraction, while the residual fraction was the most dominant solid phase pool of Cr (~81.53 %) and Ba (~57.41 %). (2) Mn, V, Co, As and Ni in the study area were consistently from natural sources. The analysis of enrichment factors indicated that urban soils in Weinan City were classified as having significant enrichment by Ba, Cu, Pb, Cr and Zn. The overall results proposed the future tactics for Weinan environment quality control on a local scale that concerned not only the levels of risky, but also the industrial emission abatement techniques as well as urban setting.

Chemical shifts observed in Lα X-ray emission lines of elements in the range of 26 ≤ Z ≤ 30 in their halogen compounds

The chemical shifts and full widths at half maximum intensity of Lα X-ray emission lines of elements in the range 26 ≤ Z ≤ 30 were studied in their halogen compounds using a wavelength-dispersive X-ray fluorescence spectrometry. It was observed that the chemical shifts for F based compounds are higher than that of Cl and Br based compounds.

Making low concentration in-house pressed pellet trace element standards for carbonate rock analyses by WD-XRF

We describe a simple method for making in-house, low concentration (0–100ppm) pressed pellet standards for analyzing Ni, Cu, Mo, V and U in carbonate lithologies by wavelength dispersive X-ray fluorescence (WD-XRF) spectrometry. This method can easily be modified to include other elements of interest and to encompass a different range of concentrations. The purpose here was to circumvent the general lack of adequate geological certified reference materials (CRMs) having the necessary concentrations of the above five elements that are commonly used in paleoceanographic studies as proxies for changes in bioproductivity and paleoredox conditions in the water column and near the sediment–water interface. Standards were prepared by spiking 99.999% pure calcium carbonate powder with single element, inductively coupled plasma mass spectrometry (ICP-MS) standard stock solutions to yield final multi-element mixtures containing 0, 1, 2, 5, 10, 20, 50 and 100ppm of Ni, Cu, Mo, V and U, independently verified using acid digestion ICP-MS and PROTrace XRF trace element analyses. The level of in-house standard homogeneity was determined statistically using ANOVA tests (analyses of variance) on count rate data generated for each analyte from three surface transects (50×500μm) ablated on each standard using laser-ablation ICP-MS, demonstrating that all are statistically distinguishable and sufficiently homogenous for the intended purposes of larger spatial scale XRF measurements. The in-house standards were then used to refine preexisting XRF calibrations based on a broad suite of non-carbonate geological CRMs. The refined calibrations yield close agreement with ICP-MS and PROTrace XRF-derived values for the suite of in-house standards when analyzed repeatedly as ‘unknown samples’ by the XRF analytical protocol. The precision of sample preparation and analysis was assessed statistically by ANOVA tests on the results of repeated analyses of analyte concentrations for replicate XRF samples prepared from a representative carbonate sample, yielding reproducibility on the order of 1) <2.5% at the 50–100ppm level, 2) within ±5–10% or better at the 10–20ppm level, 3) within ±5–15% at the 5ppm level, and 4) ±10–55% at the 1–2ppm level which approaches analytical detection limits. Analytical detection limits and residual calibration backgrounds of the XRF protocol were constrained empirically by repeated analyses of ultrapure calcite blanks.

The quantification and application of handheld energy-dispersive x-ray fluorescence (ED-XRF) in mudrock chemostratigraphy and geochemistry

Traditionally, analytical techniques such as wavelength-dispersive x-ray fluorescence (WD-XRF), inductively-coupled plasma (ICP) and mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA), or stationary (bench-top) energy-dispersive x-ray fluorescence (ED-XRF) have been used to generate quantitative geochemical results. However, a more efficient means of data collection using portable ED-XRF instrumentation now allows the investigator to acquire rapid, non-destructive, quantitative measurements on drill core and clean, flat rock surfaces, in addition to pressed powder pellets typically used in WD-XRF analysis. Similar to traditional XRF methods, quantification using the handheld ED-XRF requires a matrix-specific calibration. Unfortunately, very few internationally-accepted mudrock or shale reference materials exist, and their elemental ranges provide inadequate coverage for the geochemical diversity of mudrocks. In order to return reliable, calibrated results, a unique set of reference materials has been developed that incorporates a wide range of mudrock elemental compositions. The current method provides elemental calibrations for major elements heavier than sodium, and the following trace elements: Ba, V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Mo, Th, and U.A comparison of handheld energy-dispersive and wavelength-dispersive x-ray fluorescence (ED-XRF and WD-XRF) results from pressed powder pellets of Mississippian-age Barnett Shale of North-Central Texas, USA, is presented in order to evaluate the reliability of the reference calibration and the quantification of unknown samples using two different instrument platforms. It will be demonstrated that calibrated results from the handheld ED-XRF effectively define chemostratigraphic changes in real-time. As a consequence, quantified results can be used immediately to assess changes in bulk mineralogy, paleo-redox conditions, and to link down-core geochemical changes to stratigraphic, sedimentological, and paleoenvironmental observations.

Wavelength dispersive X-ray fluorescence analysis using fundamental parameter approach of Catha edulis and other related plant samples

This work is the first attempt to quantify trace elements in the Catha edulis plant (Khat) with a fundamental parameter approach. C. edulis is a famous drug plant in east Africa and Arabian Peninsula. We have previously confirmed that hydroxyapatite represents one of the main inorganic compounds in the leaves and stalks of C. edulis. Comparable plant leaves from basil, mint and green tea were included in the present investigation as well as trifolium leaves were included as a non-related plant. The elemental analyses of the plants were done by Wavelength Dispersive X-Ray Fluorescence (WDXRF) spectroscopy. Standard-less quantitative WDXRF analysis was carried out based on the fundamental parameter approaches. According to the standard-less analysis algorithms, there is an essential need for an accurate determination of the amount of organic material in the sample. A new approach, based on the differential thermal analysis, was successfully used for the organic material determination. The obtained results based on this approach were in a good agreement with the commonly used methods. Depending on the developed method, quantitative analysis results of eighteen elements including; Al, Br, Ca, Cl, Cu, Fe, K, Na, Ni, Mg, Mn, P, Rb, S, Si, Sr, Ti and Zn were obtained for each plant. The results of the certified reference materials of green tea (NCSZC73014, China National Analysis Center for Iron and Steel, Beijing, China) confirmed the validity of the proposed method.

Chemical effects in the Kα and Kβ1,3 of X-ray emission spectra of Fe

Chemical shifts and full widths at half maximum intensity (FWHM) of Kα and Kβ1,3 X-ray emission lines were measured for the following Fe compounds: Fe, FeCl2, FeCl3·6H2O, FeF2, FeF2·4H2O, FeF3, FeF3·3H2O, FeO3, FeS2, FeSO4. The measurements were performed with a wavelength-dispersive X-ray fluorescence spectrometry (WDXRF). It was found that the calculated results for Fe compounds are strongly correlated with the oxidation state. At the same time chemical effects for halogens compounds are generally more than that other compounds.

Effect of Co-Dopants in TiO2–SiO2 Thin films on the Formaldehyde Degradation

Titanium dioxide (TiO2)–silicon dioxide (SiO2) thin films were synthesized using the peroxo titanic acid approach (PTA) combined with the sol–gel method at low temperature around 100°C. The effects of type and amount of dopants of ferric (Fe3+) or thiourea (N-S) and co-dopants of Fe3+ and N-S on the films physicochemical properties and on the photocatalytic degradation of the methylene blue and formaldehyde under UV and visible light irradiation were investigated. Physicochemical properties of photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, wavelength-dispersive X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV–Vis spectroscopy. The results showed that the TiO2 crystal phases obtained from this method were exclusively anatase and the needle-like crystals have an average diameter of 10–25 nm. Compared with the single dopant of 1.0 wt.% Fe3+ or 0.125 wt.% N-S that was the optimal concentration for photocatalytic degradation of methylene blue and formaldehyde, the co-dopants of 0.125 wt.% N-S + 1.0 wt.% Fe3+ furthermore increased the degradation efficiency. Co-dopants of 0.125 wt.% N-S + 1.0 wt.% Fe3+ in TiO2–SiO2 films were considered to play synergistic roles in narrowing TiO2 band gap resulting in the higher methylene blue and formaldehyde degradation efficiency. Since the crystal grain size of TiO2–SiO2 films synthesized by the PTA method is small, in the visible light region, the high transmittance was attainable to 80% with no-doped and dropped to 50–60% with doped thin films.

Growth of TiO 2-based nanotubes on Ti–6Al–4V alloy

The possibility of tailoring titania nanotube films on Ti–6Al–4V alloy is investigated using electrolytes based on NH 4H 2PO 4 with the addition of different concentrations of NH 4F. Several morphologies from high aspect ratio nanotubes to barrier layers are achieved by the control of the electrolyte composition, regarding its pH and fluoride concentrations. The morphology and composition of the anodic layers were evaluated by scanning and transmission electron microscopy, Rutherford backscattering spectroscopy (RBS) and Wavelength dispersive X-ray fluorescence spectroscopy. The formation efficiency and the fluoride ions content in the nanotubes depend on the F concentration in the electrolyte. The higher concentration of fluoride ions in the electrolyte promotes an increase of the F incorporated in the nanotubes, about 12 at.% but, reduces the nanotube formation efficiency. However, no significant presence of phosphorus was detected into the films by means of the above-mentioned analytical techniques.

Enrichment and activation of smectite-poor clay

A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

Influence of the grain size on the quality of standardless WDXRF analysis of river Nile sediments

In multichannel wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) the fluorescence intensity might depend on grain size and heterogeneity of the sample. Six river Nile sediment samples were collected two meters below the water surface from different locations covering the greater Cairo, Egypt. Each sample was dried at 65°C for 48h and divided into four grain size fractions: <32μm, 32–63μm, 63–125μm and 125–200μm using different sieves. The dry sediment samples were mixed with low contamination binder (Wax, C6H8O3N2) in a mass ratio of wax:sample=4:0.9g. Sample pellets were made using a hydraulic press at a pelletizing pressure of 120KNcm−2. The results show that the XRF intensities of the Kα radiation might increase or decrease with decreasing grain size, depending on the atomic number of the analyte. In the present thick pelletized samples, the penetration depth of the characteristic radiation increases at low grain sizes, and consequently the probability of the grain-size effect on the characteristic radiation decreases. Depending on the experimental data, a general theoretical equation, relating fluorescence intensity, grain size and atomic number, was derived by using cubic spline interpolation. The fractions were identified by WDXRF using standardless quantitative analysis, depending on the fundamental parameter approach. According to the present statistical analysis and the Certified Reference Material (CRM) results, the quantitative analysis results were found acceptable when the grain size of the river Nile sediments less than 32μm. At a grain size>63μm, standardless analysis using fundamental parameter approach was found to be useful for qualitative and semi-quantitative analysis only whereas there are a strong positive correlations.

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.

Determination of Cr(III) and Cr(VI) in water by wavelength-dispersive X-ray fluorescence spectrometry after preconcentration with an ion-exchange resin disk

A rapid and simple method using an ion-exchange resin disk combined with wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry was developed for the determination of Cr(III) and Cr(VI) in water. A 100-ml water sample was first adjusted to pH 3 with nitric acid and then passed through an anion-exchange resin disk placed on top of a cation-exchange resin disk at a flow rate of 1 ml min−1 to separate Cr(III) and Cr(VI). Anionic Cr(VI) was preconcentrated on the upper anion-exchange resin disk, whereas cationic Cr(III) was preconcentrated on the lower cation-exchange resin disk. Each ion-exchange resin disk was dried at 100 °C for 30 min in an electric oven and coated with a commercially available laminate film. The specimens were measured using a WDXRF spectrometer. The calibration curves of Cr(III) and Cr(VI) showed good linearity in the range 1–10 µg. The detection limits corresponding to three times the standard deviation (n = 5) of blank values were 0.17 µg for Cr(III) and 0.16 µg for Cr(VI). If a 1-l water sample is used, these limits would be 0.17 and 0.16 µg l−1, respectively. A spike test for 50 µg l−1 Cr(III) and Cr(VI) in tap water and river water showed quantitative recoveries (94–114%), although this was not observed for mineral drinking water owing to the overlap of V Kβ with Cr Kα. The recovery after overlap correction was satisfactory (115%). Copyright © 2011 John Wiley & Sons, Ltd.

Elemental Composition in Two Water Beetles (Dytiscus thianschanicus, Dytiscus persicus) (Dytiscidae: Coleoptera) as Revealed by WDXRF Spectroscopy

In this study, concentrations of 34 different inorganic elements between Dytiscus thianschanicus and Dytiscus persicus collected from the environs of five Turkish cities were measured by wavelength dispersive X-ray fluorescence spectrometry. The two species were found to differ in both elemental composition and amount. The concentrations of Na, As, Br and Ba were found to differ significantly between D. thianschanicus and D. persicus. In addition, Mn and I concentrations for D. thianschanicus and Si, Zn for D. persicus between males and females were statistically significant. It is thought that metabolic differences between males and females of these insects may be behind the observed differences in these species. Differences in elemental composition were also seen between beetles from different localities, and the content of non-essential elements in an insect's body may be a useful measure of the level of these elements in their habitats.

Effects of Progesterone, β-Estradiol, and Androsterone on the Changes of Inorganic Element Content in Barley Leaves

The present study was performed to determine the changes in inorganic element content in barley leaves of mammalian sex hormones (MSH). Barley leaves were sprayed with 10(-4), 10(-6), 10(-9), 10(-12), 10(-15)M concentrations of progesterone, β-estradiol, and androsterone at 7th day after sowing. The plants were harvested at the end of 18days after treatment with MSH solutions. The inorganic element concentrations were determined using wavelength dispersive X-ray fluorescence spectroscopy technique. Although the all MSH concentrations significantly (p < 0.05) increased the concentrations of calcium, magnesium, phosphorus, sulfur, copper, manganese, aluminum, zinc, iron, potassium, and chlorine, it decreased those of sodium concentration in barley leaves. The maximum changes in the element concentrations were obtained at 10(-9)M for plant leaves treated with progesterone, 10(-6)M for plant leaves treated with β-estradiol and androsterone. The present study elucidated that MSH significantly (p < 0.05) affected the inorganic element concentrations in barley leaves.

Assessment of metal elements in final drug products by wavelength dispersive X-ray fluorescence spectrometry

This work demonstrates that an analytical method based on wavelength dispersive X-ray fluorescence spectrometry has an acceptable degree of linearity, precision and accuracy in a given range, which make it suitable for the purpose of determining Cu, Zn, Fe and Cr impurities in final drug products.

Characteristics of trace elements in aerosols collected in Northern Tunisia

In order to investigate the chemical characteristics of atmospheric aerosols, the sources and variability of atmospheric inputs, aerosols samples were collected during April 2006 and June 2007 in the coastal area of Boumhel, Tunisia. The samples were analysed for thirteen elements including Ca, Fe, Al, Si, Ti, Mg, Mn, K, Na, Cl, S, Zn and Pb using a wavelength dispersive X-ray fluorescence spectrometry. All elements measured in the aerosols of Boumhel revealed differences between the two seasons: the concentrations of all elements were the highest in June and the lowest in April due to the importance of meteorological conditions. The cascade impactor provided mass distributions indicate that Al, Fe, Si, Ti, Na, Cl and S are concentrated in coarse particles. The enrichment factors (EFs) of all elements indicate that Al, Fe, Si, Ca and Ti are mainly derived from soil sources. Na, S and Cl are mostly due to sea salts.

Mineralogical study of precolonial (16501850 CE) tin smelting slags from Rooiberg, Limpopo Province, South Africa

Vitreous slag remains of prehistoric tin smelting activities (1650-1850 CE) excavated at Rooiberg, Limpopo Province, South Africa were analyzed by wavelength-dispersive X-ray fluorescence spectrometry (WD-XRF), energy-dispersive X-ray spectroscopy (EDX), and electron-microprobe analysis (EPMA). The slags were found to contain high concentrations of tin oxide suggesting a low level of metal recovery that resulted in substantial tin losses. In addition, skeletal cassiterite, and complex spinels, as well as tin prills ranging in size from a few to tens of micrometres were observed. The contribution discusses the role tin(II) and (IV) oxides are thought to play during formation of slag as well as the crystal chemistry of spinels precipitated during cooling.

ESR dating of calcrete nodules from Bala, Ankara (Turkey): Preliminary results

The age of two calcrete nodules (C1 and C2) from the Bala section in the region of Ankara, Turkey, is determined by the Electron Spin Resonance (ESR) method. Three radiation-induced ESR signals at g=2.0056 (A signal), g=2.0006 (C signal) and g=2.0038 (broad signal, BL) were observed. The broad signal (BL) intensity was used as a dating signal. The properties of this dating signal are described in this manuscript. The calcrete nodules were irradiated with a (60)Co gamma source and measured with an ESR spectrometer (X-band) to obtain the signal intensity vs. dose curve and fitted well with the single exponential saturation functions. Based on this model, accumulated dose (D(E)) values for dating are obtained using the multiple-aliquot additive dose method. The D(E) values of C1 and C2 calcretes are 1880±207 and 671±67 Gy, respectively. The ESR ages of the two calcrete samples are obtained by assessing the annual dose rate (D) from the content of (238)U, (232)Th and K(2)O determined by wavelength dispersive X-ray fluorescence (XRF) spectrometry. The results are 761±120 and 419±64 ka, respectively, falling into the Middle Pleistocene Epoch in the geological time scale in agreement with the positions of the stratigraphical record.