The status of strontium in biological apatites: an XANES/EXAFS investigation

Osteoporosis represents a major public health problem through its association with fragility fractures. The public health burden of osteoporotic fractures will rise in future generations, due in part to an increase in life expectancy. Strontium‐based drugs have been shown to increase bone mass in postmenopausal osteoporosis patients and to reduce fracture risk but the molecular mechanisms of the action of these Sr‐based drugs are not totally elucidated. The local environment of Sr²⁺ cations in biological apatites present in pathological and physiological calcifications in patients without such Sr‐based drugs has been assessed. In this investigation, X‐ray absorption spectra have been collected for 17 pathological and physiological calcifications. These experimental data have been combined with a set of numerical simulations using the ab initioFEFF9 X‐ray spectroscopy program which takes into account possible distortion and Ca/Sr substitution in the environment of the Sr²⁺ cations. For selected samples, Fourier transforms of the EXAFS modulations have been performed. The complete set of experimental data collected on 17 samples indicates that there is no relationship between the nature of the calcification (physiological and pathological) and the adsorption mode of Sr²⁺ cations (simple adsorption or insertion). Such structural considerations have medical implications. Pathological and physiological calcifications correspond to two very different preparation procedures but are associated with the same localization of Sr²⁺versus apatite crystals. Based on this study, it seems that for supplementation of Sr at low concentration, Sr²⁺ cations will be localized into the apatite network.     

X‐ray fluorescence computed tomography with absorption correction for biomedical samples

To obtain accurate distributions of trace elements in biomedical samples nondestructively, the problems on absorption correction and radiation dose are confronted in X‐ray fluorescence computed tomography. In this paper, the absorption‐corrected ordered subsets expectation maximization (AC‐OSEM) algorithm is developed to solve these problems. Simulation results show that the AC‐OSEM‐based X‐ray fluorescence computed tomography is accurate when only the incident X‐ray attenuation map is known and relatively fewer projections are provided. In addition, for the biomedical samples, the simplified approximate expression of the fluorescence attenuation map is practicable. Experiments on the biomedical samples were also carried out to evaluate the applicability of the AC‐OSEM algorithm to soft tissues, which demonstrates that the distribution of the trace element Fe in the pathological liver could be clearly revealed. Copyright © 2014 John Wiley & Sons, Ltd.     

Synchrotron‐radiation‐induced oxidation of selenite to selenate in coal‐derived fly ash

Systematic changes observed in consecutive XANES spectra of selenium in samples of fly ash from a power plant in Alberta, Canada, burning subbituminous coal have been interpreted as arising from synchrotron‐radiation‐induced oxidation of a selenite species to selenate. It was estimated that about 15–20% of the selenite was oxidized to selenate during the 2 h exposure of the fly ash to the synchrotron beam. In contrast, the XANES spectra of arsenic (and other trace elements not documented herein) showed no variation. It is believed that this is the first time that radiation‐induced changes have been observed for an element in coal‐derived fly ash.     

A sub‐micrometer resolution hard X‐ray microprobe system of BL8C at Pohang Light Source

A microprobe system has been installed on the nanoprobe/XAFS beamline (BL8C) at PLS‐II, South Korea. Owing to the reproducible switch of the gap of the in‐vacuum undulator (IVU), the intense and brilliant hard X‐ray beam of an IVU can be used in X‐ray fluorescence (XRF) and X‐ray absorption fine‐structure (XAFS) experiments. For high‐spatial‐resolution microprobe experiments a Kirkpatrick–Baez mirror system has been used to focus the millimeter‐sized X‐ray beam to a micrometer‐sized beam. The performance of this system was examined by a combination of micro‐XRF imaging and micro‐XAFS of a beetle wing. These results indicate that the microprobe system of the BL8C can be used to obtain the distributions of trace elements and chemical and structural information of complex materials.     

Determination of Trace Elements in High‐Purity Palladium by Inductively Coupled Plasma Mass Spectrometry Using an Internal Standard Method

Method validation of inductively coupled plasma mass spectrometry analyses for trace impurities in high‐purity materials is often limited not only by the lack of suitable reference materials with the same matrix composition but also by the lack of a significant number of certified trace element concentrations in the available reference materials. This paper demonstrates a new and simple method for the direct determination of 44 trace elements in high‐purity palladium using inductively coupled plasma mass spectrometry and an internal standard method. Sc and In were employed as internal standards to effectively eliminate nonspectral interferences from the Pd matrix. The detection limits of the 44 trace impurities were from 0.00078 to 0.46 µg/mL and the relative standard deviations (n=6) were below 3.5%. The method was further validated using a palladium standard material (Aldrich palladium standard material, CAS no. 7440053). The analytical results are in good agreement with the certified values.     

Trace element analysis of hairs in patients with dementia

The trace elements of scalp hair samples from ≥60‐year‐old dementia patients and normal persons have been studied by X‐ray absorption near‐edge spectroscopy (XANES) in fluorescent mode and wavelength‐dispersive X‐ray fluorescence spectrometry. Comparisons of hair trace element levels of age‐matched dementia patients and normal persons revealed significantly elevated amounts of calcium, chlorine and phosphorus in dementia patients relative to normal persons. The results of XANES measurements identify the chemical forms of deposited calcium and phosphorus in the hair samples of both dementia patients and normal persons to be calcium chloride (CaCl₂) and phosphate (PO₄^3?), respectively. The amount of sulfur in hairs of dementia patients was found to be not significantly different from that in normal persons. The sulfur K‐edge XANES spectra, however, show significantly higher accumulations of sulfur in the sulfate (SO₄^2?) form in hairs of Alzheimer's disease and Parkinson's disease dementia patients. This study presents the possible roles of calcium, chlorine, phosphorus and sulfur in the etiology of dementia in elderly patients.     

微波消解ICP-AES法分析九种补血类中药元素

采用微波消解法处理样品,以电感耦合等离子体发射光谱法(ICP-AES)测定并分析九种补血类中药中Zn,Mn,Na,K,Ca,Mg,Ni,Pb,Se,Fe,Cu,Al,B,Ti,Sn,Hg和Li元素的含量。结果显示,九种补血类中药富含有益于人体健康的主要及微量元素,其中众所周知补血类元素Fe,Se,Ni,Mn,Zn含量较高。九种补血中药按各大元素分类(大量元素,必需元素,非必需元素,有害元素)分布于柱形直方图。应用主成分分析和聚类分析于数据矩阵去评价元素分析结果。聚类分析的结果显示九种补血类中药中十七种元素的含量所形成的树状系统图主要分为三个集群。通过优化微波消解条件,各元素的回收率均在97.89%～103.25%之间,相对标准偏差均小于3.0%。ICP-AES结合微波消解法可以精确和准确地测定九种补血类中药中的元素。     

Quantitative major and trace elemental mapping by PIXE of concretionary pyrite from the Witwatersrand Basin,South Africa

Several concretionary pyrite grains displaying multiple, massive sulphide or silicate inclusion‐rich, annuli from two gold‐bearing reef horizons (Ventersdorp Contact Reef, Kimberley Reefs) in different parts of the Witwatersrand Basin were analysed by particle‐induced X‐ray emission (PIXE) and electron microprobe analysis (EMPA) for their major and trace element compositions. Both PIXE spot analysis and mapping of the distributions of major and trace elements were carried out, and EMPA was employed to obtain major element abundances for matrix corrections of PIXE analysis. Spatial analysis by PIXE is excellent in comparison with EMPA, as PIXE detection limits are lower by 1–2 orders of magnitude at comparable, short‐duration counting times (12 h for 4096 pixel analyses by PIXE). EMPA was successful in the identification of individual zones, for example on the basis of locally enriched minor elements Ni or As. This technique also provided essential standard‐based control on major element abundances for the standardless PIXE dynamic analysis. The compositional results obtained on concretionary pyrite grains by PIXE are distinctly different for each analysed grain, in terms of relative enrichment of certain minor and trace elements in specific zones. Gold was detected locally in the interiors of grains and/or along grain margins. The different results are discussed with regard to their possible meaning related to the origin of gold mineralization in the Witwatersrand ore deposit. Copyright © 2004 John Wiley & Sons, Ltd.     

X‐ray spectromicroscopy in soil and environmental sciences

X‐ray microscopy is capable of imaging particles in the nanometer size range directly with sub‐micrometer spatial resolution and can be combined with high spectral resolution for spectromicroscopy studies. Two types of microscopes are common in X‐ray microscopy: the transmission X‐ray microscope and the scanning transmission X‐ray microscope; their set‐ups are explained in this paper. While the former takes high‐resolution images from an object with exposure times of seconds or faster, the latter is very well suited as an analytical instrument for spectromicroscopy. The morphology of clusters or particles from soil and sediment samples has been visualized using a transmission X‐ray microscope. Images are shown from a cryo‐tomography experiment based on X‐ray microscopy images to obtain information about the three‐dimensional structure of clusters of humic substances. The analysis of a stack of images taken with a scanning transmission X‐ray microscope to combine morphology and chemistry within a soil sample is shown. X‐ray fluorescence is a method ideally applicable to the study of elemental distributions and binding states of elements even on a trace level using X‐ray energies above 1 keV.     

Synchrotron XANES and ED‐XRF analyses of fine‐paste ware from 13th to 14th century maritime Southeast Asia

The combination of energy dispersive X‐ray fluorescence (ED‐XRF) and synchrotron X‐ray absorption near‐edge structure (XANES) provides the detailed composition of fine‐paste ware (FPW) kendis, dated back to 13th–14th century maritime Southeast Asia. Sources of clay and production sites were classified according to Al₂O₃, SiO₂, α‐Fe₂O₃ and γ‐Fe₂O₃ as well as trace elements. The similarities based on these components provided another evidence of a trade route between Kota Cina in North Sumatra of Indonesia and Kok Moh on Satingphra Peninsula, a well‐known production area in present‐day Thailand. In additions, the uniquely large contribution of α‐Fe₂O₃ in XANES spectra suggests that Nakhon Si Thammarat province of Thailand could also be one of FPW production areas in maritime Southeast Asia. Copyright © 2017 John Wiley & Sons, Ltd.     

Influences of Branched Side Chains and Cross‐linking Network on the Solid State Structures of Oligo‐ and Poly (p‐phenyleneethynylene)s

To investigate the influences of side chains and cross‐linking network on the packing fashion and the formation of aggregates and excimers of poly(p‐phenyleneethynylene)s (PPEs) chains in the solid state, a series of cross‐linkable unsubstituted oligo (p‐phenyleneethynylene)s (OPEVs) and alkoxy‐substituted PPEs (EO‐PPEVs) with vinyl end‐groups were synthesized and characterized. By a thermal cross‐linking reaction, cross‐linked polymers were obtained. The oligomer chains in the cross‐linked polymers containing no residual vinyls are packed randomly, forming no aggregates or excimers; however, aggregates and excimers exist in the cross‐linked polymers if they contain residual vinyls. The chains of EO‐PPEVs with sterically hindered side chains form aggregates in films. The network, leading to a pronounced increase of the film photoluminescence quantum yields, can depress these aggregates. These EO‐PPEVs are fully processable and can become insoluble in normal organic solvents after thermal curing; therefore, they are favorable candidates as active layers for fabrication of high performance multilayer devices.     

Accumulation of minor and trace elements in lichens in and around Kolkata,India: an application of X‐ray fluorescence technique to air pollution monitoring

A recent environmental survey has listed Kolkata, a megacity in Eastern India, as one of the most polluted cities in the world. Rapid urbanization and industrialization have resulted in an alarming increase in the level of air pollution in the city. Epiphytic lichens have extensively been used worldwide as bioindicators of environmental quality. They are very responsive to environmental stressors, especially gaseous pollutants and particulates including trace elements and heavy metals. This work describes application of energy dispersive X‐ray fluorescence, a fast multi‐elemental analytical technique, for estimating concentration of trace elements of lichen samples collected from sites in and around Kolkata. The results indicate that the samples from sites burdened with heavy vehicular load together with pollution from various industries and factories have significantly higher concentration of elements such as S, Ca, V, Cr, Mn, Fe, Ni and Pb as compared to those collected from sites having less or no load. Remarkable seasonal variation is also noted in the concentration of the elements such as Mn, Fe, Cu, Zn and Pb. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparison of trace elements analysis of nephrite samples from different deposits by PIXE and ICP‐AES

Comparing values of trace elements determined by external‐beam proton‐induced X‐ray emission (PIXE) and inductively coupled plasma atomic emission spectrometry (ICP‐AES) is important to find the provenience of raw materials of ancient nephrite artifacts, because most previous elemental characterizations of nephrite minerals were obtained by ICP‐AES, but PIXE presents the possibility of nondestructive analysis for largely and integrally ancient nephrite artifacts. In this work based on 12 nephrite minerals, it shows that the distribution of trace elements of nephrite samples both in PIXE and ICP‐AES data are generally consistent, although large differences exist in some elements. According to the trace elements, the two types of nephrite mineralization origins can be distinguished, determined by PIXE and ICP‐AES, respectively. Moreover, depending on the PIXE and ICP‐AES data, Sr can be regarded as fingerprint element of Xiaomeiling nephrite minerals, and the differentiation of Sr content between Xiaomeiling nephrite minerals and ancient nephrite artifacts from Liangzhu culture (3300–2300 bc ) is clear evidence that the raw materials of the artifacts are not from Xiaomeiling deposit. The nephrite minerals from Wenchuan deposit can be distinguished from other samples because of their high values of Mn/Fe. Therefore, the PIXE can be used with ICP‐AES to judge mineralization mechanism and find fingerprint elements of raw materials of ancient nephrite artifacts. Copyright © 2012 John Wiley & Sons, Ltd.     

Fish otolith trace element maps: new approaches with synchrotron microbeam x‐ray fluorescence

Otoliths, the carbonate earstones of fishes, take up minor and trace amounts of elements as they accrete through a fish's life. We apply synchrotron microbeam x‐ray fluorescence methods to establish a breakthrough in high‐resolution, simultaneous area mapping of multiple trace elements in otoliths, with spatial resolution down to 20 µm and trace element detection down into the part per million range for multiple elements. Concentration maps of Ca, Sr, Zn and, for the first time, Ba, Mn, and Se are obtained simultaneously. Combinations of these elemental maps provide new insights into the environmental history of fishes and their lifetime movements, illustrated by several case studies. This method helps pave the way toward improved spatial analysis of otolith microchemistry. Copyright © 2007 John Wiley & Sons, Ltd.     

New Materials for Solid‐Phase Extraction of Trace Elements

Abstract

The development of new sorbents and their application in preconcentration methods for determination of trace elements is a subject of great interest. This review summarizes and discusses several analytical methods involving the preparation and use of new solid‐phase materials. The performance and general properties of sorbents such as carbon nanotubes, imprinted ions, biosorbents, nanoparticles, and fullerene are discussed in detail. The perspective and future trends in the use of these materials are also considered.     

Application of high‐energy polarized energy‐dispersive x‐ray fluorescence spectrometry to the determination of trace levels of As,Hg, and Pb in certifiable color additives

Advances in x‐ray fluorescence (XRF) using high‐energy polarized energy‐dispersive (ED)XRF spectrometry (PEDXRF) were applied to the determination of trace As, Hg, and Pb in various color additives subject to batch certification by the U.S. Food and Drug Administration (FDA). The objectives of this study were to simplify sample preparation for quantitative determination of these elements and, if possible, to achieve improved sensitivity and detection limits compared to techniques currently used for certification. PEDXRF was compared with wavelength‐dispersive x‐ray fluorescence spectrometry (WDXRF) and inductively coupled plasma – mass spectrometry (ICP‐MS) for the analysis of trace levels of As, Hg, and Pb in certifiable color additives. For these light matrices, PEDXRF provided better signal‐to‐noise and allowed quantitation in smaller amounts of color additive relative to WDXRF and equal or better precision to ICP‐MS. Determination of these trace elements in a variety of color additives was possible relative to calibrations generated from one color additive using specimens prepared simply by pouring the color additive powder into an XRF sample cup. Published 2016. This article is a U.S. Government work and is in the public domain in the USA     

Spectroscopic investigations on kidney stones using Fourier transform infrared and X‐ray fluorescence spectrometry

Kidney stone is the most painful and prevalent urological disorder of the urinary system throughout the world. Thus, analysis of kidney stones is an integral part in the evaluation of patents having stone disease. Spectroscopic investigations of stones provide an idea about the pathogenesis of stones for its better cure and treatment. Hence, the present work targets multispectroscopic investigations on kidney stones using Fourier transform infrared (FTIR) and wave dispersive X‐ray fluorescence (WD‐XRF) spectroscopy which are the most useful analytical methods for the purpose of bio‐medical diagnostics. In the present study, FTIR spectral method is used to investigate the chemical composition and classification of kidney stones. The multicomponents of kidney stones such as calcium oxalate, hydroxyl apatite, phosphates, carbonates, and struvite were investigated and studied. Qualitative and quantitative determination of major and trace elements present in the kidney stones was performed employing WD‐XRF spectroscopy. The wide range of elements determined in the kidney stones were calcium (Ca), magnesium (Mg), phosphorous (P), sodium (Na), potassium (K), chlorine (Cl), sulfur (S), silicon (Si), iodine (I), titanium (Ti), iron (Fe), ruthenium (Ru), zinc (Zn), aluminum (Al), strontium (Sr), nickel (Ni), copper (Cu), and bromine (Br). For the first time, ruthenium was detected in kidney stone samples employing WD‐XRF in very low concentration. Our results revealed that the presence and relative concentrations of trace elements in different kinds of stones are different and depend on the stone types. From the experiments carried out on kidney stones for trace elemental detection, it was found that WD‐XRF is a robust analytical tool that can be useful for the diagnosis of urological disorders. We have also compared our findings with the results reported using XRF technique. The results obtained in the present paper show interesting prospects for FTIR and WD‐XRF spectrometry in nephrolithiasis. Copyright © 2017 John Wiley & Sons, Ltd.     

Total reflection x‐ray fluorescence analysis—a review

Total reflection x‐ray fluorescence analysis (TXRF) is a special energy‐dispersive x‐ray analytical technique extending XRF down to the ultra trace element range. Detection limits of picograms or nanograms per gram levels are reached with x‐ray tube excitation. Using synchrotron radiation as excitation source, femtogram levels are detectable, particularly important for Si wafer surface analysis. TXRF is specially suited for applications in which only a very small amount of sample is available, as only a few micrograms are required for the analysis. In this review, an overview of theoretical principles, advantages, instrumentation, quantification and application is given. Chemical analysis as well as surface analysis including depth profiling and thin‐film characterization is described. Special research results on extension to low‐Z elements, excitation with synchrotron radiation and x‐ray absorption spectroscopy (XAS) for chemical speciation at trace levels are reviewed. Copyright © 2007 John Wiley & Sons, Ltd.     

Ordered Networks of Gold Nanoparticles Crosslinked by Dithiol‐Oligomers

Controlled aggregation of nanoparticles into superlattices is a grand challenge in material science, where ligand based self‐assembly is the dominant route. Here, the self‐assembly of gold nanoparticles (AuNPs) that are crosslinked by water soluble oligo‐(ethylene glycol)‐dithiol (oEG‐dithiol) is reported and their 3D structure by small angle X‐ray scattering is determined. Surprisingly, a narrow region is found in the parameter space of dithiol linker‐length and nanoparticle size for which the crosslinked networks form short‐ranged FCC crystals. Using geometrical considerations and numerical simulations, the stability of the formed lattices is evaluated as a function of dithiol length and the number of connected nearest‐neighbors, and a phase diagram of superlattice formation is provided. Identifying the narrow parameter space that allows crystallization facilitates focused exploration of linker chemical composition and medium conditions such as thermal annealing, pH, and added solutes that may lead to superior and more robust crystals.