Determination of cobalt marker in cow ruminal fluid by EDXRF and SRTXRF

This article describes a comparison of conventional energy‐dispersive X‐ray fluorescence (EDXRF) and synchrotron radiation total‐reflection X‐ray fluorescence (SRTXRF) for Co determination in ruminal fluid from Holstein cow. This element is used as marker for animal nutrition studies. For EDXRF, 200 µl of the sample were dried on 6.35 µm Mylar film at 60 °C. The excitation was carried out using an X‐ray tube with Mo target and Zr filter operated at 30 kV/20 mA. For SRTXRF, 10 µl of the sample were pipetted on a Lucite carrier and dried at 60 °C. In both the techniques, Ga was used as internal standard and the acquisition time was 200 s. The trueness of both techniques was evaluated through the standard addition method, the recoveries obtained by SRTXRF and EDXRF were 76 and 99%, and the limits of detection, 13 and 240 µg l^?1, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Methodology for the determination of minor and trace elements in petroleum cokes by wavelength‐dispersive X‐ray fluorescence (WD‐XRF)

This article describes a methodology for the analysis of minor and trace elements in petroleum cokes by wavelength‐dispersive X‐ray fluorescence (WD‐XRF) spectrometry. The methodology was developed in order to have a rapid and reliable control method of these elements, because they determine coke end uses. There are a number of standard methods of chemical analysis by WD‐XRF or inductively coupled plasma atomic emission spectrometry (ICP‐OES) techniques. However, the standards that use WD‐XRF measurement give detection limits (L_D) above 10 mg·kg^?1 and only analyse a few elements of interest, whereas the ICP‐OES method requires extensive sample handling and long sample preparation times, with the ensuing errors. In order to improve the method described in the standard ASTM D6376 and reach the L_D and quantification limits (L_Q) required, the different stages of the process, ranging from sample preparation to measurement conditions: analytical line, detector, crystal, tube power, use of primary beam filters, and measurement time, were optimised. The samples were prepared in the form of pressed pellets, under conditions of high cleanliness of the mills, crushers, presses, and dies, and of the laboratory itself. The following reference materials were used in measurement calibration and validation: SRM 1632c, SRM 2718, SRM 2719, SRM 2685b, AR 2771, AR 2772, SARM 18, SARM 19, and CLB‐1. In addition, a series of materials were analysed by WD‐XRF and ICP‐OES, and the results were compared. The developed methodology, which uses WD‐XRF, is rapid and accurate, and very low L_D and measurement uncertainties were obtained for the following elements: Al, Ba, Ca, Cr, Cu, Fe, Ge, K, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, and Zn. Copyright © 2010 John Wiley & Sons, Ltd.     

X‐ray fluorescence analysis of Co,Ni, Pd,Ag, and Au in the scrapped printed‐circuit‐board ash

A method for the quantitative analysis of Co, Ni, Pd, Ag, and Au in the scrapped printed‐circuit‐board ash by X‐ray fluorescence (XRF) spectrometry using loose powder was developed. The printed‐circuit‐board samples were converted to ash pyrolytically in porcelain crucibles by sequential heating using a gas burner and electric furnace, and then were ground with a ball mill. The calibrating standards were prepared by adding the appropriate amounts of NiO powder and aqueous standard solutions containing Co, Pd, Ag, and Au to the base mixtures of Al₂O₃ (5.0 mass%), SiO₂ (49 mass%), CaCO₃ (11 mass%), Fe₂O₃ (3.3 mass%), and CuO (30 mass%) as a matrix. Then, 10 g of the resulting mixtures were dried and homogenized for 90 min with a V‐type mixing machine. Specimens for XRF analysis were prepared from the so‐called loose‐powder method in which powder samples were compacted into a hole (12.0‐mm diameter and 5.0‐mm height) in an acrylic plate and covered with a 6‐µm thickness of polypropylene film. Matrix effects were corrected using the intensity value of Compton scattering for PdKα, AgKα, and AuLβ₂, and that of background scattering at 35.8° (2θ) for CoKα and NiKα. The detection limits corresponding to three times the standard deviation of the blank intensity were 2.5–45 µg g^?1. The proposed method was validated against the pressed‐powder‐pellet method by comparing the calibration curves. Moreover, the concentrations of Co, Ni, Pd, and Ag determined using the proposed XRF method were approximately the same as those resulting from an atomic‐absorption‐spectrometric analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly Water‐Dispersible,Highly Conductive,and Biocompatible Polypyrrole‐Coated Silica Particles Stabilized and Doped by Chondroitin Sulfate

Currently available methods to prepare conducting polymers‐coated colloidal substrates for biomedical applications need to be improved because they involve the use of toxic reagents and tend to result in aggregated products with diminished conductivity. The work herein describes for the first time a facile strategy for preparing highly water‐dispersible, highly conductive, and biocompatible polypyrrole‐coated silica core–shell (SiO₂@PPy) particles using only chondroitin sulfate (CS), a biologically derived polymer, as the stabilizer and dopant. The CS preadsorbed onto silica surface serves as a template to control the confined growth of the PPy shell and doping of in situ polymerized PPy shell. The thickness of the PPy shell can be tuned from 8 to 17 nm by varying the CS preadsorbed amount. Increasing the thickness of the adsorbed CS layer can control the deposition of thinner PPy shells on an SiO₂ core surface to provide highly water‐dispersible SiO₂@PPy particles. Moreover, CS‐doped SiO₂@PPy particles exhibit conductivities as high as 5.3 S cm^?1. The conductivity of the particles depends on the PPy mass loading and the doping level of the PPy shell. Furthermore, the SiO₂@PPy particles exhibit good biocompatibility and therefore have potential applications in biomedicine.     

X‐ray fluorescence determination of Cs,Ba, La,Ce, Nd,and Ta concentrations in rocks of various composition

The technique has been developed for the quantification of small tantalum, cesium, barium, lanthanum, cerium, and neodymium concentration in rocks with X‐ray wavelength dispersive spectrometer S8 TIGER (Bruker AXS, Germany). The optimum conditions have been chosen for registration of the analyzed elements characteristic radiation and background positions. To determine the concentrations of analyzed elements accurately, the contribution of overlapping lines to the experimental intensities of the analytical lines has been taken into account. The sample of mass about 1.2 g has been pressed into pellet by the hydraulic press. Metrological studies showed that the accuracy in the determination of the concentration of analyzed elements for the developed technique meets the requirements for methods of III accuracy class. The Ta detection limits calculated for TaL_β1‐analytical and CsL_α1‐analytical lines were 2.6 and 3.4 ppm, respectively. The detection limit of Ba, La, Ce, and Nd was (in ppm), respectively, 4.3, 2.7, 5.8, and 4.7. The metrological characteristics of the previously developed and adapted techniques were compared. Ta concentration in granite pegmatite samples has been quantified. The samples of the highest tantalum content have been investigated additionally by powder diffraction and X‐ray microprobe analysis. The X‐ray diffraction method turned out to be insensitive to the detection of mineral phase of tantalum niobates, while micro‐XRF allowed detecting its presence in tourmaline grains. Copyright © 2017 John Wiley & Sons, Ltd.     

4‐Alkyl‐2,2,6,6‐tetramethyl‐1,4,2,6‐oxaazadisilinanes: synthesis,structure, and conformational analysis

4‐Alkyl‐2,2,6,6‐tetramethyl‐1,4,2,6‐oxaazadisilinanes RN[CH₂Si(Me)₂]₂O [R = Me ( 1 ), i‐Pr ( 2 )] were synthesized by two methods which provided good yields up to 84%. Low temperature NMR study of compounds ( 1 ) and ( 2 ) revealed a frozen ring inversion with the energy barriers of 8.5 and 7.7 kcal/mol at 163 and 143 K, respectively, which is substantially lower than that for their carbon analog, N‐methylmorpholine. DFT calculations performed on the example of molecule ( 1 ) showed that N? Me_ax conformer to exist in the sofa conformation with the coplanar fragment C? Si? O? Si? C, and its N? Me_eq conformer in a flattened chair conformation. Copyright © 2009 John Wiley & Sons, Ltd.     

Calibration of the MER α‐particle x‐ray spectrometer for detection of ‘invisible’ OH and H2O possibly present in Martian rocks and soils

An existing Monte Carlo code was modified and extended to predict the intensity ratio of elastically and inelastically scattered plutonium Lα x‐rays incident on rock samples in the Mars Exploration Rover's α‐particle x‐ray spectrometer (APXS) device. The systematics of the scatter ratio as a function of effective sample atomic number are explored. The simulated Rayleigh/Compton ratios (R/C)_sim are compared with measured ratios (R/C)_meas that are obtained by fitting APXS spectra of geochemical reference materials using an x‐ray fluorescence version of GUPIX. The quantity K = (R/C)_meas/(R/C)_sim is then plotted against the mean atomic number of the sample to provide a calibration for known samples. Departures of K values of unknown samples from this calibration may then be attributed to the presence of light, ‘invisible’ elements in the sample. This work is part of an ongoing project aimed at developing methods to quantify bound water in Martian rocks analyzed by the present and the next generation APXS instruments. Copyright © 2006 John Wiley & Sons, Ltd.     

Standard‐free composition measurements of Alx In1–xN by low‐loss electron energy loss spectroscopy

We demonstrate a standard‐free method to retrieve compositional information in Al_x In_1–xN thin films by measuring the bulk plasmon energy (E_p), employing electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). Two series of samples were grown by magnetron sputter epitaxy (MSE) and metal organic vapor phase epitaxy (MOVPE), which together cover the full com‐ positional range 0 ≤ x ≤ 1. Complementary compositional measurements were obtained using Rutherford backscattering spectroscopy (RBS) and the lattice parameters were obtained by X‐ray diffraction (XRD). It is shown that E_p follows a linear relation with respect to composition and lattice parameter between the alloying elements from AlN to InN allowing for straightforward compositional analysis. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

FT‐Raman,FT‐IR spectra and DFT calculations on monomeric and dimeric structures of 5‐fluoro‐ and 5‐chloro‐salicylic acid

The experimental and theoretical study on the structures and vibrations of 5‐fluoro‐salicylic acid and 5‐chloro‐salicylic acid (5‐FSA and 5‐ClSA, C₇H₅FO₃ and C₇H₅ClO₃) is presented. The Fourier transform infrared spectra (4000–400 cm⁻¹) and the Fourier transform Raman spectra (4000–50 cm⁻¹) of the title molecules in the solid phase were recorded. The molecular structures, vibrational wavenumbers, infrared intensities, Raman intensities and Raman scattering activities were calculated for a pair of molecules linked by the intermolecular O H···O hydrogen bond. The geometrical parameters and energies of 5‐FSA and 5ClSA were obtained for all eight conformers/isomers from density functional theory (DFT) (B3LYP) with 6‐311++G(d,p) basis set calculations. The computational results identified the most stable conformer of 5‐FSA and 5‐ClSA as the C1 form. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The spectroscopic and theoretical results were compared with the corresponding properties for 5‐FSA and 5‐ClSA monomers and dimer of C1 conformer. The optimized bond lengths, bond angles and calculated wavenumbers showed the best agreement with the experimental results. Copyright © 2010 John Wiley & Sons, Ltd.     

Switching of hydrogen bonds of water in ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate

We have investigated temperature‐induced Raman spectral changes of deuterated water in an ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF₄]), between room temperature and 77 K. The comparison of the OH and OD stretching vibrational spectra at 77 K shows that the strength of the hydrogen bonds in [bmim][BF₄]–water mixtures strongly depends on the type of water, i.e. H₂O and D₂O. In the [bmim][BF₄]–D₂O system, remarkably strong hydrogen bonds form at low temperatures, but they switch to nearly free hydrogen bonds on heating. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrogen bonding and excited state properties of the photoexcited hydrogen‐bonded (E)‐S‐(2‐aminopropyl) 3‐(4‐hydroxyphenyl)prop‐2‐enethioate complexes

The time‐dependent density functional theory (TDDFT) method has been performed to investigate the excited state and hydrogen bonding dynamics of a series of photoinduced hydrogen‐bonded complexes formed by (E)‐S‐(2‐aminopropyl) 3‐(4‐hydroxyphenyl)prop‐2‐enethioate with water molecules in vacuum. The ground state geometric optimizations and electronic transition energies as well as corresponding oscillator strengths of the low‐lying electronic excited states of the (E)‐S‐(2‐aminopropyl) 3‐(4‐hydroxyphenyl)prop‐2‐enethioate monomer and its hydrogen‐bonded complexes O₁‐H₂O, O₂‐H₂O, and O₁O₂‐(H₂O)₂ were calculated by the density functional theory and TDDFT methods, respectively. It is found that in the excited states S₁ and S₂, the intermolecular hydrogen bond formed with carbonyl oxygen is strengthened and induces an excitation energy redshift, whereas the hydrogen bond formed with phenolate oxygen is weakened and results in an excitation energy blueshift. This can be confirmed based on the excited state geometric optimizations by the TDDFT method. Furthermore, the frontier molecular orbital analysis reveals that the states with the maximum oscillator strength are mainly contributed by the orbital transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital. These states are of locally excited character, and they correspond to single‐bond isomerization while the double bond remains unchanged in vacuum.     

On the potential of Raman‐spectroscopy‐based carbonate mass spectrometry

The potential for using Raman spectroscopy to measure stable oxygen isotope ratios (¹⁸O/¹⁶O) in carbonates is evaluated by measuring the Raman spectra and isotope ratios of a suite of 60 synthesized, ¹⁸O‐enriched calcite crystals ranging in composition from natural abundance (0.2 mole‐% ¹⁸O) to 1.2 mole‐% ¹⁸O. We determined the Raman‐inferred isotopic ratios (R_Raman) by fitting curves to the ν₁ symmetric stretching peak at 1086 cm⁻¹ and the smaller satellite peak, associated with the ν₁ stretching mode of singly substituted carbonate groups (C¹⁶O₂¹⁸O) at 1065 cm⁻¹. The ratio of the two peak areas shows a 1:1 correspondence with the ¹⁸O/¹⁶O ratios derived from standard mass spectrometry methods, confirming that the relative intensities of the ν₁ symmetric stretching peaks is a direct measure of the isotopic ratio in the carbonates. The 1‐sigma uncertainties of the R_Raman values of the individual crystals were 0.00079 (384‰ PDB) and 0.00043 (210‰ PDB) for the four‐crystal sample means. This level of uncertainty is much too high to provide significant estimates of natural variability; however, there are multiple prospects for improving the accuracy and precision of the technique. Carbon isotope ratios in carbonates cannot be measured by our approach, but our results highlight the potential of Raman‐based isotope ratio measurement for C and other elements in minerals and organic compounds. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of heavy metal distributions along 15 m soil profiles using EDXRF,XRD, SEM‐EDX,and ICP‐MS techniques

The research of soil contamination by heavy metal is an important field due to its environmental and health implications. The goal was to study the elemental mobility as a function of depth. For this reason, the distribution of heavy metals (V, Cr, Co, Ni, Cu, Zn, As, Sn, and Pb) was investigated along soil profiles up to a depth of 15 m at 9 sampling sites in the Nilufer industrial district (Bursa, Turkey). Elemental analyses were done with the Epsilon 5 energy dispersive X‐ray fluorescence and inductively coupled plasma mass spectrometry equipment. Particle analysis was performed with a JEOL scanning electron microscope equipped with a Si(Li) X‐ray detector. The crystallographic compositions of oxide compounds in soil samples were identified by a Rigaku X‐ray diffraction instrument. Different parameters such as the soil's chemical (mineralogical structure, pH, and electrical conductivity) and physical properties (the number of blows, the stiffness index, the liquidity index, the plasticity index, and the water content) were analyzed. To assess the mobility of the heavy metals, diffusion (D) and convection coefficients (?) were calculated with the finite difference method. Convection was determined to dominate the studied region. In addition, the mobility coefficient was determined for each metal. High mobilities were determined for Zn and V, moderate mobilities for Cr, Ni, Cu, and As, and low mobilities were determined for Co and Pb. The results revealed that elements had reached depths of up to 15 m, causing irreversible soil contamination that may lead to environmental health issues.     

Thermolysis and photolysis of 2‐ethyl‐4‐nitro‐1(2H)‐isoquinolinium hydroperoxide

The thermal and light‐induced O ? O bond breaking of 2‐ethyl‐4‐nitro‐1(2H)‐isoquinolinium hydroperoxide (IQOOH) were studied using ¹H NMR, steady‐state UV/vis spectroscopy, femtosecond UV/vis transient absorption (fs TA) and time‐dependent density functional theory (TD DFT) calculations. Thermal O ? O bond breaking occurs at room temperature to generate water and the corresponding amide. The rate of this reaction, k = 5.4 · 10^?6 s^?1, is higher than the analogous rates of simple alkyl and aryl hydroperoxides; however, the rate significantly decreases in the presence of small amounts of methanol. The calculated structure of the transition state suggests that the thermolysis is facilitated by a 1,2 proton shift. The photochemical process yields the same products, as confirmed using NMR and UV/vis spectroscopy. However, the quantum yield for the photolysis is low (Φ = 0.7%). Fs TA studies provide additional detail of the photochemical process and suggest that the S₁ state of IQOOH undergoes fast internal conversion to the ground state, and this process competes with the excited‐state O ? O bond breaking. This result was supported by the fact that the model compound IQOH exhibits similar excited‐state decay lifetimes as IQOOH, which is assigned to the S₁ → S₀ internal conversion. Copyright © 2013 John Wiley & Sons, Ltd.     

Li‐, Sb‐ and Ta‐modified (K,Na)NbO3 nanopowder prepared via a water‐based sol–gel method

Stable Li‐, Sb‐ and Ta‐modified (K, Na)NbO₃ (LTS‐KNN) sol and gel were successfully prepared via an economical water‐based sol–gel method. Simultaneous thermogravimetry and differential scanning calorimetry (TG‐DSC) and X‐ray diffraction showed that organic compounds were eliminated and a pure perovskite phase formed around 600 °C. Transmission electron microscopy showed that the LTS‐KNN particle size was in the range of 11–34 nm after decomposition at 600 °C. Moreover, high performance LTS‐KNN ceramic was successfully prepared at a low sintering temperature of 1000 °C by use of the nanopowder, and its room‐temperature d₃₃, K_p, K and loss are 311 pC/N, 46.8%, 1545 and 0.024, respectively. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

In‐situ X‐ray photoelectron spectroscopy of trimethyl aluminum and water half‐cycle treatments on HF‐treated and O3‐oxidized GaN substrates

We have investigated the effect of trimethyl aluminum (TMA) and water (H₂O) half‐cycle treatments on HF‐treated, and O₃‐oxidized GaN surfaces at 300 °C. The in‐situ X‐ray photoelectron spectroscopy results indicate no significant re‐growth of Ga–O–N or self‐cleaning on HF‐treated and O₃‐oxidized GaN substrates with exposure to water and TMA. This result is different from the self‐cleaning effect of Ga₂O₃ seen on sulfur‐treated GaAs or InGaAs substrates. O₃ causes aggressive oxidation of GaN substrate and direct O–N bonding compared to H₂O. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Polarized micro‐Raman study of Al2O3‐based directionally solidified oxide eutectics containing GdAlO3 perovskite,Er3Al5O12 garnet and cubic ZrO2

The paper reports on the Raman signature of GdAlO₃ perovskite and Er₃Al₅O₁₂ garnet in melt‐grown eutectic composites, which contain α‐alumina and cubic zirconia also. Different wavelengths were used to discriminate the Raman signal from fluorescence of the rare‐earth elements. Fourteen out of the 24 Raman active perovskite modes were identified. Mode symmetry is proposed for 12 of them, based on the polarization of the light backscattered by a rotated sample. Twenty‐one out of 25 Raman active modes of the garnet were listed and assigned by straight comparison with those of the parent compounds. Copyright © 2009 John Wiley & Sons, Ltd.     

Extending the quantitative analytical capabilities of the EDXRF technique for plant‐based samples

The energy‐dispersive x‐ray fluorescence (EDXRF) technique has limitations in the quantitative analysis of light elements (low‐Z analytes with Z < 10), for many reasons. This work, however, circumvents the problem through an a priori determination of low‐Z analytes, representative of plant‐based samples. The main purpose of this work was to characterize the major elements in the dark matrix of some plant‐based samples (including biomonitors) using Rutherford backscattering spectrometry (RBS), and the results provided as a generalized input for EDXRF analysis. The derived stoichiometry and mass ratio for the moss, lichen, and cotton cellulose samples analyzed were found to be similar and close to C₇H₁₀O₅, with an average matrix of C = 49.8%, H = 4.0% and O = 45.8%. Quantitative analysis of plant‐based reference material IAEA‐336 (lichen) was subsequently carried out. Use of the a priori determined dark matrix elements (from one‐time RBS spectrometry) extended the scope of applicability of the EDXRF quantitative methods used, and improved accuracy in the elemental analysis of plant‐based samples. The results obtained were in good agreement with the reference values. Copyright © 2004 John Wiley & Sons, Ltd.     

Experimental L x‐ray fluorescence cross‐sections for elements with 45 ≤ Z ≤ 50 at 7 keV by synchrotron radiation photoionization

L x‐ray fluorescence cross‐sections for elements with 45 ≤ Z ≤ 50 were measured at 7 keV using synchrotron radiation photoionization. The experimental set‐up provided a linearly polarized monoenergetic photon beam producing a low background and improving the signal‐to‐noise ratio. The data obtained for the L lines, Ll, Lα, Lβ_I, Lβ_II, Lγ_I and Lγ_II, were grouped considering the transition scheme, the energies of the emission lines and the detector resolution. Results for the experimental cross‐sections obtained were compared with theoretical values using two different data tables. In general, it was found that the experimental fluorescence cross‐sections are slightly higher (7–10%) than the theoretically calculated data and in some cases these differences are up to 40%. Copyright © 2005 John Wiley & Sons, Ltd.     

X‐ray fluorescence analysis of sludge ash from sewage disposal plant

Glass bead/x‐ray fluorescence spectrometry of the sludge incineration ashes generated in sewage processing was developed for the determination of ten major components (Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, MnO, Fe₂O₃) and five minor elements (Zn, Cu, Cr, As, Pb). Sewage sludge ashes consisted of rock‐forming minerals and phosphate crystals that had been used for phosphorus removal. Ash samples were melted and molded with lithium tetraborate to 35 mm diameter glass disks in a Pt–Au crucible. Analytical results of ten major components and five minor elements agreed well with the recommended values of a phosphate rock standard reference material (NIST SRM 694). Elemental compositions of sewage sludge ash from seven sewage‐processing plants in Japan were determined using this method. Concentrations of Fe₂O₃, SiO₂, and CaO, along with loss of ignition in sewage sludge ash mutually differed among the sewage‐processing plant products. Seasonal variations in concentrations of ten major components and five minor components of ash samples produced from October 2001 to September 2002 were determined using the proposed method. Concentrations of SiO₂increased with the inflow of gravel by rainfall, thereby decreasing concentrations of P₂O₅ originating from excreta and microorganisms. Copyright © 2008 John Wiley & Sons, Ltd.