C. Streli

Bone Material Quality in Transiliac Bone Biopsies of Postmenopausal Osteoporotic Women After 3 Years of Strontium Ranelate Treatment

Strontium ranelate (SrR) is a relatively new treatment for osteoporosis. In this study we investigated its potential impact on human bone material quality in transiliac bone biopsies from postmenopausal osteoporotic women treated 3 years with calcium and vitamin D plus either 2 g SrR per day or placebo. Bone mineralization density distribution (BMDD), strontium (Sr) concentration, collagen cross‐link ratio, and indentation modulus were analyzed by quantitative backscattered electron imaging, electron‐induced X‐ray fluorescence analysis, synchrotron radiation induced micro X‐ray fluorescence elemental mapping, Fourier transform infrared imaging, and nanoindentation, respectively. The BMDD of SrR‐treated patients was shifted to higher atomic numbers (Zmean +1.5%, p < .05 versus placebo). We observed Sr being preferentially incorporated in bone packets formed during SrR treatment up to 6% atom fraction [Sr/(Sr + Ca)] depending on the SrR serum levels of the individuals (correlation r = 0.84, p = .018). Collagen cross‐link ratio was preserved in SR‐treated bone. The indentation modulus was significantly decreased in younger versus older bone packets for both placebo‐ (−20.5%, p < .0001) and SrR‐treated individuals (−24.3%, p < .001), whereas no differences were found between the treatment groups. In conclusion, our findings indicate that after SrR treatment, Sr is heterogeneously distributed in bone and preferentially present in bone packets formed during treatment. The effect of SrR on BMDD seems to be due mainly to the uptake of Sr and not to changes in bone calcium content. Taken together, these data provide evidence that the investigated bone quality determinants at tissue level were preserved in postmenopausal osteoporotic women after 3‐year treatment with 2 g SrR per day plus calcium and vitamin D.

Spatial distribution of the trace elements zinc, strontium and lead in human bone tissue.

Trace elements are chemical elements in minute quantities, which are known to accumulate in the bone. Cortical and trabecular bones consist of bone structural units (BSUs) such as osteons and bone packets of different mineral content and are separated by cement lines. Previous studies investigating trace elements in bone lacked resolution and therefore very little is known about the local concentration of zinc (Zn), strontium (Sr) and lead (Pb) in BSUs of human bone. We used synchrotron radiation induced micro X-ray fluorescence analysis (SR μ-XRF) in combination with quantitative backscattered electron imaging (qBEI) to determine the distribution and accumulation of Zn, Sr, and Pb in human bone tissue. Fourteen human bone samples (10 femoral necks and 4 femoral heads) from individuals with osteoporotic femoral neck fractures as well as from healthy individuals were analyzed. Fluorescence intensity maps were matched with BE images and correlated with calcium (Ca) content. We found that Zn and Pb had significantly increased levels in the cement lines of all samples compared to the surrounding mineralized bone matrix. Pb and Sr levels were found to be correlated with the degree of mineralization. Interestingly, Zn intensities had no correlation with Ca levels. We have shown for the first time that there is a differential accumulation of the trace elements Zn, Pb and Sr in BSUs of human bone indicating different mechanisms of accumulation.

Analytical possibilities of total reflection X-ray spectrometry (TXRF) for trace selenium determination in soils.

Selenium content of soils is an important issue due to the narrow range between the nutritious requirement and toxic effects upon Se exposure. However, its determination is challenging due to low concentrations within complex matrices that hamper the analysis in most spectroscopic techniques. In this study, we explored the possibilities of several analytical approaches combined with total reflection X-ray (TXRF) spectrometry for soil Se determinations. The direct analysis of a solid suspension using 20 mg of fine ground material (<50 μm) has a relatively high Se limit of detection (LOD) of 1 mg/kg (worldwide Se average in soils = 0.4 mg/kg) and is therefore only suitable for seleniferous soils. Several fast and simple analytical strategies were developed to decrease matrix effects and improve the LOD for Se determination in soil digests. On one hand, the application of a liquid-liquid extraction procedure using ethyl ether and the introduction of a Cr absorbent in the instrument configuration were carried out to avoid the associated problems on TXRF analysis of soil extracts due to the high Fe concentrations (∼700 mg/L). On the other hand, a dispersive liquid-liquid microextraction procedure (DLLME) before the TXRF analysis of the soil digest was also developed. The effects of various experimental parameters such as sample volume, effect of major elements present in the soil matrix (Fe), and Se concentration in the sample were investigated. The LOD using this analytical methodology (0.05 mg/kg of Se) was comparable to or lower than those obtained in previous works using other popular spectrometric techniques such as GFAAS, ICPMS, and AFS. The calculated Se concentration for JSAC-0411 ([Se] = 1.32 ± 0.27 mg/kg) using the combination of DLLME and TXRF ([Se] = 1.40 ± 0.23 mg/kg) was in agreement with the certified value.

2013 Atomic spectrometry update—A review of advances in X-ray fluorescence spectrometry

This review describes advances in the continued expansion of work using the XRF group of techniques published approximately between April 2013 and March 2014. Specialised laboratory instrumentation, X-ray sources, detector development and data processing continue unabated. It is remarkable how quickly hand-held XRF instrumentation has developed to the point where many examples of its use are included in the various application sections of this review, rather than in the instrumentation section. Several new beam lines and their new end-stations were described in publications from SR research centres around the world. More analysts are attracted to TXRF and related techniques with new sample preparation techniques offered for an expanding range of applications. Nanoparticles and nanomaterials feature throughout this review particularly in clinical, biological and environmental studies. A novel approach for the reuse of industrial by-products described how acid mine drainage sludge and coal fly ash facilitated the problem of the high levels of phosphate present in waste waters (cow dung) from the dairy industry. The archaeological and cultural heritage section often includes good news stories. This year we learn how an XRF mapping technique was used to show that Pablo Picasso used a popular brand of French house paint in his works of art.

Low Z total reflection X-ray fluorescence analysis — challenges and answers ☆

Low Z elements, like C, O, ... Al are difficult to measure, due to the lack of suitable low-energy photons for efficient excitation using standard X-ray tubes, as well as difficult to detect with an energy dispersive detector, if the entrance window is not thin enough. Special excitation sources and special energy dispersive detectors are required to increase the sensitivity and to increase the detected fluorescence signal and so to improve the detection limits. Synchrotron radiation, due to its features like high intensity and wide spectral range covering also the low-energy region, is the ideal source for TXRF, especially of low-Z elements. Experiments at a specific beamline (BL 3-4) at SSRL, Stanford, designed for the exclusive use of low-energy photons has been used as an excitation source. Detection limits <100 fg for Al, Mg and Na have been achieved using quasimonochromatic radiation of 1.7 keV. A Ge(HP) detector with an ultra-thin NORWAR entrance window is used. One application is the determination of low-Z surface contamination on Si-wafers. Sodium, as well as Al, are elements of interest for the semiconductor industry, both influencing the yield of ICs negatively. A detection capacity of 1010 atoms/cm2 is required which can be reached using synchrotron radiation as excitation source. Another promising application is the determination of low-Z atoms implanted in Si wafers. Sodium, Mg and Al were implanted in Si-wafers at various depths. From measuring the dependence of the fluorescence signal on the glancing angle, characteristic shapes corresponding to the depth profile and the relevant implantation depth are found. Calculations are compared with measurements. Finally, aerosols sampled on polycarbonate plates in a Battelle impactor were analyzed with LZ-TXRF using multilayer monochromatized Cr-Kα radiation from a 1300-W fine-focus tube for excitation. Results are presented.

Analytical approaches for Hg determination in wastewater samples by means of total reflection X-ray fluorescence spectrometry

At present, there is a considerable interest in Hg monitoring in wastewater samples due to its widespread occurrence and the high toxicity of most of its compounds. Hg determination in water samples by means of total reflection X-ray fluorescence spectrometry (TXRF) entails some difficulties due to the high vapor pressure and low boiling point of this element that produce evaporation and loss of Hg from the surface of the reflector during the drying process, commonly used for sample preparation in TXRF analysis. The main goal of the present research was to develop a fast and simple chemical strategy to avoid Hg volatilization during the analysis of wastewater samples by TXRF spectrometry. Three different analytical procedures were tested for this purpose: (i) increasing the viscosity of the wastewater sample by adding a non-ionic surfactant (Triton X-114), (ii) Hg immobilization on the quartz reflectors using the extractant tri-isobutylphosphine (Cyanex 471X) and (iii) formation of a stable and non-volatile Hg complex into the wastewater sample. The best analytical strategy was found to be the formation of a Hg complex with thiourea (pH=10) before the deposition of 10 microL of sample on the reflector for following TXRF analysis. Analytical figures of merit such as linearity, limits of detection, accuracy and precision were carefully evaluated. Finally, the developed methodology was applied for the determination of Hg in different types of wastewater samples (industrial effluents, municipal effluents from conventional systems and municipal effluents from constructed wetlands).

2016 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and its applications

This review describes advances in the XRF group of techniques published approximately between April 2015 and March 2016. Fundamental contributions in the instrumentation sections include the development of synchrotron radiation sources, semiconductor design technology and evaluating the quality of in situ hand-held XRF results. A bench top TXRF spectrometer for the measurement of the elements from carbon to uranium is described that offers achievable detection limits that range from ng g−1 to μg g−1. The applications sections aim to give a representative overview of the range of applications that use XRF techniques with an emphasis on papers that describe technical or application innovation. Sample size investigated ranged from the planet Mercury down to nano-gram quantities of cement secreted by settlement stage barnacle larvae. The archaeological and cultural heritage section this year includes an authentic report on the use of cannabis as a filler in ancient lime plaster and heartening news that the construction of an underground parking garage in the centre of Zurich (Switzerland) unearthed the remains of seven Neolithic settlements from the 4th and 3rd millennium BC. The X-ray excitation of iron present in ancient iron-gall inks was presented as a step toward the non-invasive reading of fragile and/or unopenable documents. Feedback from readers of this review is most welcome and the review coordinator may be contacted using the email address provided.

TXRF with synchrotron radiation Analysis of Ni on Si-wafer surfaces

Abstract SR-TXRF (Synchrotron Radiation excited Total Reflection X-ray Fluorescence Analysis) with monoenergetic radiation produced by a W C multilayer monochromator has been applied to the analysis of Ni on a Si-wafer surface. An intentionally contaminated wafer with 100 pg has been used to determine the detection limits. 13 fg have been achieved for Ni at a beam current of 73 mA and extrapolated to 1000 s. This technique simulates the sample preparation technique of Vapour Phase Decomposition (VPD) on a wafer surface.

Complex forming competition and in-vitro toxicity studies on the applicability of di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) as a metal chelator

Di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) is a potential candidate in chelation therapy as an iron chelator. This study showed that a combined treatment with 2μM easily available Fe(II), Cu(II) and Zn(II) each and 5μM Dp44mT on eight different cancer cell lines resulted in a 10-40-fold increase in the intracellular Cu content compared to control samples. The uptake of Cu and Cu-dependent cytotoxicity strictly depend on the Cu concentration of the culture medium. Even as low concentration of Dp44mT as 0.1μM can transport high amounts of copper inside the cells. The Cu accumulation and toxicity through Dp44mT can hardly be influenced by Fe. Copper uptake and toxicity triggered by 2μM extracellular Cu(II) and 5μM Dp44mT could not be influenced by Fe(II) extracellular concentrations even 50-times higher than that of Cu(II). A 50-times higher Co(II) extracellular concentration hindered the Cu(II) uptake almost completely and a 10-times higher Co(II) concentration already decreased the Dp44mT-mediated Cu toxicity. Conditional complex stability constant determinations for Dp44mT with Cu(II), Co(II), Fe(II), Ni(II) and Zn(II) revealed that the metal-to-ligand ratio is 1:1 in [Cu(II)Dp44mT] complex, while for Co(II), Fe(II) and Ni(II) is 1:2. The highest stability constant was obtained for Cu(II) (lg β=7.08±0.05) and Co(II) (lg β2=12.47±0.07). According to our results, Dp44mT in combination with Cu is highly toxic in vitro. Therefore, the use of Dp44mT as an iron chelator is limited if biologically available Cu is also present even at low concentrations.

Analysis of organic contaminants on Si wafers with TXRF- NEXAFS

Abstract Organic contamination is starting to play an important role in the production and quality control of Si wafers. For the traceability of the source of contamination, information on the chemical binding conditions is very valuable. A near edge X-ray absorption fine structure (NEXAFS) investigation is the natural development of total reflection X-ray fluorescence (TXRF) analysis of the wafer surfaces able to solve the problem of speciation. The plane grating monochromator beamline for undulator radiation of the Physikalisch-Technische Bundesanstalt at the electron storage ring BESSY II, which provides photon energies between 30 eV and 1.9 keV for the specimen excitation, is an ideal excitation source for TXRF-NEXAFS experiments that require a high resolving power and a sufficient photon flux for trace analysis of low Z elements. The contaminants have been diluted and deposited as droplets on wafer pieces thoroughly cleaned after the cutting. The K edges of C, N, O have been examined. Some discrepancies have been found in the analysis of the same compounds in two different beamtimes; molecular orientation is pointed to as the cause for the difference in magnitude of the resonances. The unintentional contamination has been identified as mainly composed of aliphatic chains.