Determination of lead at physiological level in human biological materials using the total reflection X‐ray fluorescence analysis

Total reflection X‐ray fluorescence (TXRF) analysis was applied in determination of low concentration of lead in samples of human biological materials. The determination of lead in human serum and hair samples is presented as an example. In serum samples, lead concentration was in the range from 0.013 to 0.051 μg/g (median 0.024 μg/g). The reference ranges of lead content in hair are from 1.41 to 4.08 μg/g for men and from 1.18 to 3.29 μg/g for women groups, respectively. Because of Pb concentration range close to the detection limit of the TXRF method, the measurement needed evaluation of the best analytical conditions. This paper presents the results of this evaluation, namely internal standard selection, measurement conditions, and quantitative calibration of the spectrometer. Finally, as a result of evaluation, the detection limit was found on the level 0.001 μg/g (water solution) and about 0.005 μg/g for human hair samples and 0.007 μg/g for serum samples. The obtained values reach nearly the physiological lead level. The presented results are of practical importance for lead concentration studies in human biological materials using the TXRF method. Copyright © 2016 John Wiley & Sons, Ltd.     

Zr and Ba edge phenomena in the scintillation intensity of fluorozirconate‐based glass‐ceramic X‐ray detectors

The energy‐dependent scintillation intensity of Eu‐doped fluorozirconate glass‐ceramic X‐ray detectors has been investigated in the energy range from 10 to 40 keV. The experiments were performed at the Advanced Photon Source, Argonne National Laboratory, USA. The glass ceramics are based on Eu‐doped fluorozirconate glasses, which were additionally doped with chlorine to initiate the nucleation of BaCl₂ nanocrystals therein. The X‐ray excited scintillation is mainly due to the 5d–4f transition of Eu²⁺ embedded in the BaCl₂ nanocrystals; Eu²⁺ in the glass does not luminesce. Upon appropriate annealing the nanocrystals grow and undergo a phase transition from a hexagonal to an orthorhombic phase of BaCl₂. The scintillation intensity is investigated as a function of the X‐ray energy, particle size and structure of the embedded nanocrystals. The scintillation intensity versus X‐ray energy dependence shows that the intensity is inversely proportional to the photoelectric absorption of the material, i.e. the more photoelectric absorption the less scintillation. At 18 and 37.4 keV a significant decrease in the scintillation intensity can be observed; this energy corresponds to the K‐edge of Zr and Ba, respectively. The glass matrix as well as the structure and size of the embedded nanocrystals have an influence on the scintillation properties of the glass ceramics.     

Effects of organic ligands on Pb absorption and speciation changes in Arabidopsis as determined by micro X‐ray fluorescence and X‐ray absorption near‐edge structure analysis

Pb can pass through the food chain via plants and threaten human health, which has attracted widespread attention. Changes in Pb speciation affect its bioavailability in soils and water. However, whether organic ligands can change the uptake and mobility of Pb in plants and increase or decrease Pb bioavailability remains uncertain. To reveal the roles of organic and inorganic Pb in Pb metabolism in plants, the localization and speciation changes of Pb in Arabidopsis thaliana plants grown in organic and inorganic Pb were characterized by synchrotron radiation micro X‐ray fluorescence and X‐ray absorption near‐edge structure, respectively. These results demonstrated that Arabidopsis absorbed more Pb from Pb(NO₃)₂ than Pb(CH₃COO)₂ at the same exposure concentration. A higher percentage of Pb‐citrate was found in Arabidopsis exposed to inorganic Pb solution, which suggested that Pb‐citrate was the main complex for root‐to‐shoot transportation in Arabidopsis exposed to inorganic Pb solutions. Pb complexed with the organic ligand CH₃COO^? significantly inhibited primary root growth and lateral root development, while, at the same time, Pb was blocked by root hairs, which represented another way to reduce Pb absorption and protect the plant from biotoxicity.     

ICP-AES法测定金属硅中的Al、B、Ba、Ca、Cr、Cu、 Fe、Mg、Mn、Ni、Sr、Ti、V和Zn杂质元素

本文提供了一种测定金属硅中Ｂ,Ｆｅ,Ａｌ,Ｃａ,Ｍｎ等１４个杂质元素的ＩＣＰ－ＡＥＳ方法,在样品处理过程中,加入适量体积的甘露醇能够抑制Ｂ的挥发。用本方法测定了一个国家地球化学标准样（ＧＳＲ－４）,结果令人满意。     

X‐ray fluorescence induced by standing waves in the grazing‐incidence and grazing‐exit modes: study of the Mg–Co–Zr system

The characterization of Mg–Co–Zr tri‐layer stacks using X‐ray fluorescence induced by X‐ray standing waves, in both the grazing‐incidence (GI) and the grazing‐exit (GE) modes, is presented. The introduction of a slit in the direction of the detector improves the angular resolution by a factor of two and significantly improves the sensitivity of the technique for the chemical characterization of the buried interfaces. By observing the intensity variations of the Mg Kα and Co Lα characteristic emissions as a function of the incident (GI mode) or detection (GE mode) angle, it is shown that the interfaces of the Si/[Mg/Co/Zr]_×30 multilayer are abrupt, whereas in the Si/[Mg/Zr/Co]_×30 multilayer a strong intermixing occurs at the Co‐on‐Zr interfaces. An explanation of this opposite behavior of the Co‐on‐Zr and Zr‐on‐Co interfaces is given by the calculation of the mixing enthalpies of the Co–Mg, Co–Zr and Mg–Zr systems, which shows that the Co–Zr system presents a negative value and the other two systems present positive values. Together with the difference of the surface free energies of Zr and Co, this leads to the Mg/Zr/Co system being considered as a Mg/Co_xZr_y bi‐layer stack, with x/y estimated around 3.5.     

The Br,Fe, Rb,Sr, and Zn contents and interrelation in intact and morphologic normal prostate tissue of adult men investigated by energy‐dispersive X‐ray fluorescent analysis

A method for radionuclide‐induced (¹⁰⁹Cd) energy‐dispersive X‐ray fluorescent (EDXRF) was used to determine Br, Fe, Rb, Sr, and Zn contents in intact and morphologic normal prostate tissues. Prostates were removed at necropsy from 64 men (mean age 36.5 years, range 13–60) who had died suddenly. All materials were divided into two parts. One part was morphologically examined, whereas chemical element contents of the other were estimated. Mean values (M ± SΕΜ) for mass fraction of Br, Fe, Rb, Sr, and Zn (mg kg^?1 on dry‐weight basis) in the intact and morphologic normal prostate tissue were 35.5 ± 4.0, 107 ± 5.4, 17.1 ± 0.8, 1.9 ± 0.3, and 850 ± 79, respectively. Mean values (M ± SΕΜ) for Zn/Fe, Zn/Rb, and Zn/Sr ratios of mass fraction were 8.72 ± 0.80, 57.4 ± 7.2, and 567 ± 82, respectively. A strongly pronounced tendency of age‐related exponential increase in Zn mass fraction as well an increase in Zn/Fe, Zn/Rb, and Zn/Sr ratios in prostate was observed. A significant positive correlation was seen between the prostatic zinc and iron contents (p ≤ 0.05, r = 0.22) and between the prostatic zinc and bromine contents (p ≤ 0.01, r = 0.43). Copyright © 2011 John Wiley & Sons, Ltd.     

Investigation of short‐range structural order in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 glasses,using X‐ray absorption spectroscopy and ab initio molecular dynamics simulations

Short‐range order has been investigated in Zr_69.5Cu₁₂Ni₁₁Al_7.5 and Zr_41.5Ti_41.5Ni₁₇ metallic glasses using X‐ray absorption spectroscopy and ab initio molecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass‐forming abilities (Zr_41.5Ti_41.5Ni₁₇ > Zr_69.5Cu₁₂Ni₁₁Al_7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.     

In‐situ X‐ray diffraction study of an electric field induced phase transition and giant strain in Na0.5Bi0.5TiO3–x %BaTiO3 lead‐free single crystals

A giant electric field (E) induced strain of ε = 0.60% has been observed for Na_0.5Bi_0.5TiO₃–5.6%BaTiO₃ single crystals under E = 20 kV/cm at 130 °C. In‐situ X‐ray diffraction (XRD) revealed that this induced transition was between pseudocubic and tetragonal structures. Our work provides a potential alternative to lead‐based piezoelectric materials. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Application of the background standard method for the determination of Rb,Sr, Y,Zr, and Nb contents in phosphorites by x‐ray fluorescence

The aim of the present work is to demonstrate the application of the x‐ray fluorescence (XRF) technique to the determination of Rb, Sr, Y, Zr, and Nb contents in phosphorites. The effect of a chemical sample composition on fluorescence intensities of analytical lines has been taken into account using the background standard method. A novelty of the work is the detailed study of a background to choose the background position, free from the spectral line overlaps of the elements presented in the sample. The most suitable background position is the position at the angle 2θ = 29° when using the analyzing crystal LiF(200). During our investigation we faced a problem of choice of Certified Reference Materials (CRMs) for the calibration of the phosphorites. To estimate interelement effects and to choose CRMs for the calibration the intensities were theoretically calculated. The statistical processing of analytical results of the technique is carried out. This technique may be applied to the determination of Rb, Sr, Y, Zr, and Nb contents in the phosphorites. Also, the possibility has been demonstrated to use the XRF technique for geochemical investigations of rocks. Phosphorites of Bokson‐Khubsugul Basin were selected as an example. As a result of the investigation the genetic type of phosphorites was established, which corresponded to the present geodynamical depositional environment. The character of the distribution of Rb, Sr, Y, Zr, and Nb contents in the phosphorites was also studied. Copyright © 2008 John Wiley & Sons, Ltd.     

Characterisation of inorganic pigments in ancient glass beads by means of Raman microspectroscopy,microprobe analysis and X‐ray diffractometry

Ancient coloured glass beads from Sri Lanka and Oman were analysed by Raman microspectroscopy for non‐destructive identification of inorganic pigments in the glass. Calcium phosphate (Ca₃(PO₄)₂), cassiterite (SnO₂), cuprite (Cu₂O) and a Pb(Sn,Si)O₃‐type lead tin oxide were found to be used as colouring agents. Moreover, a distinction between lead‐based and alkali‐based glass matrices could be made. Electron microprobe analysis and X‐ray diffractometry were performed to show the capability of Raman microspectroscopy in comparison to these methods for answering archaeometric questions. Copyright © 2006 John Wiley & Sons, Ltd.     

Determination of Pb,As, Cd and trace elements in polluted soils near a lead–zinc mine using polarized X‐ray fluorescence spectrometry and the characteristics of the elemental distribution in the area

Polarization energy dispersive X‐ray fluorescence spectrometry was used in the determination of Pb, As and Cd, as well as Cr, Cu, Zn, Ni and other minor and trace elements in the soil samples taken from a polluted area by lead mine exploitation. Two difficulties have to be overcome. One is strong overlap of Pb Lα over As Kα and another is lack of suitable certified reference materials. The different excitation conditions and analytical lines were tried to reduce the impact of overlap of Pb Lα over As Kα. When KBr was used as the second target, compared with Zr, the proportion from Pb Lα was reduced about six times. Even so, however, the overlap was not reduced enough to be ignored. The inductively coupled plasma atomic emission spectrometry and mass spectrometry methods were used to analyze parts of soil samples and provide data for compensating lack of reference materials. By this method, the analytical concentration range of Pb, As and Cd were significantly extended. The analytical range of Pb, As and Cd were 1.4 µg/g~4.2%, 0.6 µg/g~9.3% and 0.5 µg/g~1500 µg/g, respectively. The high concentrations of Pb, As and Cd were found in the samples in the vicinity of the Pb‐Zn mine. The concentrations of Pb, As, Cd, Zn and Cu were higher than the Class III in the Chinese environmental quality standard for soils. The highest concentrations of Pb, As, Cd and Zn in the soil samples were 14 960, 2726, 65 and 9439 µg/g, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Elemental and chemical state depth analysis by combined use of a polycapillary and a thin wire in a synchrotron X‐ray microprobe

A simple method is proposed to improve the depth resolution of a conventional X‐ray confocal microscopy system by adding a thin wire close to the sample surface and upstream of the polycapillary in the exit channel. A depth resolution of around 10 μm is easily obtained. The detection efficiency is improved by a factor of two to three times, compared with the thin wire technique previously proposed. It is also shown that not only the elemental distribution but also the X‐ray absorption near‐edge structure (XANES) spectrum from locations below the sample surface can be obtained. Copyright © 2017 John Wiley & Sons, Ltd.     

A protocol for searching the most probable phase‐retrieved maps in coherent X‐ray diffraction imaging by exploiting the relationship between convergence of the retrieved phase and success of calculation

Coherent X‐ray diffraction imaging (CXDI) is a technique for visualizing the structures of non‐crystalline particles with size in the submicrometer to micrometer range in material sciences and biology. In the structural analysis of CXDI, the electron density map of a specimen particle projected along the direction of the incident X‐rays can be reconstructed only from the diffraction pattern by using phase‐retrieval (PR) algorithms. However, in practice, the reconstruction, relying entirely on the computational procedure, sometimes fails because diffraction patterns miss the data in small‐angle regions owing to the beam stop and saturation of the detector pixels, and are modified by Poisson noise in X‐ray detection. To date, X‐ray free‐electron lasers have allowed us to collect a large number of diffraction patterns within a short period of time. Therefore, the reconstruction of correct electron density maps is the bottleneck for efficiently conducting structure analyses of non‐crystalline particles. To automatically address the correctness of retrieved electron density maps, a data analysis protocol to extract the most probable electron density maps from a set of maps retrieved from 1000 different random seeds for a single diffraction pattern is proposed. Through monitoring the variations of the phase values during PR calculations, the tendency for the PR calculations to succeed when the retrieved phase sets converged on a certain value was found. On the other hand, if the phase set was in persistent variation, the PR calculation tended to fail to yield the correct electron density map. To quantify this tendency, here a figure of merit for the variation of the phase values during PR calculation is introduced. In addition, a PR protocol to evaluate the similarity between a map of the highest figure of merit and other independently reconstructed maps is proposed. The protocol is implemented and practically examined in the structure analyses for diffraction patterns from aggregates of gold colloidal particles. Furthermore, the feasibility of the protocol in the structure analysis of organelles from biological cells is examined.     

Lβ2 satellites in the X‐ray emission spectra of elements 72Hf, 73Ta, 74W, 81Tl, 83Bi and 92U

The satellite spectra arising due to the L₃M_x–M_xN_4,5 (x = 1–5) transition array in the X‐ray emission spectra of ₇₂Hf, ₇₃Ta, ₇₄W, ₈₁Tl, ₈₃Bi and ₉₂U have been calculated using available HFS data on K–LM and L–MN Auger transition energies. The agreement between the calculated and measured energies, that between calculated and measured separations in energies and the consideration of the relative probabilities of all the L₃M_x–M_xN_4,5 transitions have been used as the basis for deciding the origin of the satellites. It has been established that two satellites observed in the Lβ₂ region of the X‐ray spectra of various elements, named β₂^I and β₂^II in the order of increasing energy, are mainly emitted by the L₃M_4,5–M_4,5N_4,5 transitions. It is observed that satellite β₂^I in the spectra of elements with ₇₂Hf to ₇₄W has been assigned to the superposition of the ³F₄–³G₅ and ³F₄–³D₃ transitions and must be the most intense one among all these satellites. The same transition has been proved to be the main origin of satellite β₂^II, reported in the element with ₈₁Tl, ₈₃Bi and ₉₂U. Further, satellite β₂^I, reported in the spectra of elements with ₈₁Tl and ₉₂U, has been associated with the transitions ³D₃–³F₄ and ¹D₂–¹F₃. Finally, line β₂^II, reported in the spectra of elements with Z = 72–74, has been assigned to the ¹F₃–¹G₄ and ³P₀–³D₁ transitions. The possible contributions of other transitions of the L₃M_x–M_xN_4,5 (x = 1–5) array having intensities comparable with those of the above transitions, as well as the corresponding lines that have not yet been observed, have also been discussed. Copyright © 2011 John Wiley & Sons, Ltd.