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Powder Samples (powder + sample)
Selected AbstractsCrystal growth and twinned crystal structure of Sr2CaWO6ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010G. Madariaga Single crystals of Sr2CaWO6 have been prepared by sintering at high temperature. Powder samples were compressed into rods and heated up to 1953,K. This seems a promising new route for further studies of the structure and physical properties of double perovskites. The structural model of Sr2CaWO6 includes a quantitative description of the twinning shown by the diffraction pattern that should be present in almost any single-crystal specimen for this type of compound. [source] Optical absorption and EPR spectral studies of vauqueliniteCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2006K. Nagamuni Reddy Abstract Vauquelinite - a mineral - was investigated by EPR, NIR and optical spectroscopic techniques. EPR studies on powder sample confirm the presence of Cu(II) and Fe(III) impurity in the mineral. Optical absorption spectrum also indicates that Cu(II) impurity is present in rhombically distorted octahedral structure and Fe(III) in octahedral structure. NIR results are due to water fundamentals and phosphate combination tone. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Symmetrization of diffraction peak profiles measured with a high-resolution synchrotron X-ray powder diffractometerJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2006H. Hibino The asymmetry of diffraction peak profiles observed with a high-resolution synchrotron powder X-ray diffractometer has been successfully removed by a double deconvolution method. In the first step, the asymmetry caused by the axial divergence aberration of the diffractometer is removed by a whole-pattern deconvolution method based on an a priori theoretical model for the aberration. In the second step, the residual asymmetry, the origin of which can be ascribed to the aberrations of the beamline optics, is also removed by a whole-pattern deconvolution method, based on an empirical model derived from the analysis of experimental diffraction peak profiles of a standard Si powder (NIST SRM640b). The beamline aberration has been modelled by the convolution of a pseudo-Voigt or Voigt function with an exponential distribution function. It has been found that the angular dependence of the asymmetry parameter in the exponential function is almost proportional to tan,, which supports the idea that the residual asymmetry should be ascribed mainly to the intrinsic asymmetry in the spectroscopic distribution of the source X-ray supplied by the beamline optics of the synchrotron facility. Recently developed procedures of whole-pattern deconvolution have been improved to treat the singularity of the instrumental function in the measured angular range. Formulae for the whole-pattern deconvolution based on the Williamson,Hall-type dependence of the width parameter of the instrumental function have also been developed. The method was applied to the diffraction intensity data of a standard ZnO powder sample (NIST SRM674) measured with a high-resolution powder diffractometer on beamline BL4B2 at the Photon Factory. The structure parameters of ZnO were refined from the integrated peak intensities, which were extracted by an individual profile fitting method applying symmetric profile models. The refined structure parameters coincide fairly well with those obtained from single-crystal data. [source] Diffraction peak profiles from spherical crystallites with lognormal size distributionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2003T. Ida An efficient and accurate method to evaluate the theoretical diffraction peak profiles from spherical crystallites with lognormal size distribution (SLN profile) is presented. Precise results can be obtained typically by an eight-term numerical integral for any values of the parameters, by applying an appropriate substitution of the variable to the integral formula. The calculated SLN profiles have been verified by comparison with those calculated by inverse Fourier transform from the exact analytical solution of the Fourier-transformed SLN profile. It has been found that the shape of the SLN profile strongly depends on the variance of size distribution. When the logarithmic standard deviation , of the size distribution is close to 0.76, the SLN profile becomes close to a Lorentzian profile, and `super-Lorentzian' profiles are predicted for larger values of ,, as has been concluded by Popa & Balzar [J. Appl. Cryst. (2002), 35, 338,346]. The intrinsic diffraction peak profiles of an SiC powder sample obtained by deconvolution of the instrumental function have certainly shown `super-Lorentzian' line profiles, and they are well reproduced by the SLN profile for the value , = 0.93. [source] A comparison of EDI with solvent-free MALDI and LDI for the analysis of organic pigmentsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2008Ichiro Kudaka Abstract To evaluate the applicability of EDI to material analysis as a new ionization method, a comparison of EDI with solvent-free matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) was made for the analysis of organic pigments, e.g. Pigment Yellow 93, Pigment Yellow 180, and Pigment Green 36, as test samples, which are poorly soluble in standard solvents. In EDI, the samples were prepared in two ways: deposition of suspended samples in appropriate solvents and dried on the substrate, and the direct deposition of the powder samples on the substrate. No matrices were used. Both sample preparation methods gave similar mass spectra. Equally strong signals of [M + H]+ and [M , H], ions were observed with some fragment ions for azo pigments in the respective positive or negative mode of operation. For the powder sample of the phthalocyanine pigment PG36, M+, and [M + H]+ in the positive mode and M,, in the negative mode of operation were observed as major ions. Positive-mode, solvent-free MALDI gave M+, [M + H]+ and [M + Na]+ and negative mode gave [M , H], depending on the sample preparation. As solvent-free MALDI, EDI was also found to be an easy-to-operate, versatile method for the samples as received. Copyright © 2008 John Wiley & Sons, Ltd. [source] A conformational polymorphic transition in the high-temperature ,-form of chlorpropamide on cooling: a new ,,-formACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2009Tatiana N. Drebushchak Structural changes in the high-temperature ,-polymorph of chlorpropamide, 4-chloro- N -(propylaminocarbonyl)benzenesulfonamide, C10H13ClN2O3S, on cooling down to 100,K and on reverse heating were followed by single-crystal X-ray diffraction. At temperatures below 200,K the phase transition into a new polymorph (termed the ,,-form) has been observed for the first time. The polymorphic transition preserves the space group Pna21, is reversible and is accompanied by discontinuous changes in the cell volume and parameters, resulting from changes in molecular conformation. As shown by IR spectroscopy and X-ray powder diffraction, the phase transition in a powder sample is inhomogeneous throughout the bulk, and the two phases co-exist in a wide temperature range. The cell parameters and the molecular conformation in the new polymorph are close to those in the previously known ,-polymorph, but the packing of the z-shaped molecular ribbons linked by hydrogen bonds inherits that of the ,-form and is different from the packing in the ,-polymorph. A structural study of the ,-polymorph in the same temperature range has revealed no phase transitions. [source] The incommensurately modulated crystal structure of ,-Pb2BiVO6: interpretation of the phase transition ,,,,, and conduction properties of related materialsACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2009Pascal Roussel A new polymorph of Pb2BiVO6 was prepared under ambient conditions and its crystal structure was determined by single-crystal X-ray diffraction. The phase transitions ,,, and ,,, were identified in the mother phase; the high-temperature form ,-Pb2BiVO6 eventually decomposes at 753,K to a mixture of Pb4BiVO8 and the high-temperature form of PbBiVO5 before showing recombination at 923,K. ,-Pb2BiVO6 has an incommensurate monoclinic modulated structure. This crystal structure is twinned and complementary structural investigations of a powder sample of ,-Pb2BiVO6 by TEM diffraction studies confirmed the lattice and incommensurate modulation character. Log , = f(T,1) dependences for Pb2BiVO6 -related materials (6% M -for-V-substituted compositions; M = Cr, Mn, P) are reported, which allow the characterization (Ea and isothermal , values) of the ,- as well as the ,- and ,-Pb2BiVO6 varieties. [source] High-precision measurement of internuclear distances using solid-state NMRCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2008Jae-Seung Lee Abstract Today, nuclear magnetic resonance (NMR) is among the most efficient tools in structural studies. Measurement of interatomic distances is the most common way of determining high-resolution structures of molecules using NMR techniques. In this article, we describe NMR techniques for static powder samples, based on a two-dimensional single-echo scheme, enhanced with adiabatic cross-polarization. They can significantly increase the accuracy of measuring internuclear distances and turn NMR into a high-precision crystallographic technique, complementing the X-ray, and neutron-scattering methods. Experimental examples are presented for intramolecular CN and CC distances in ,-crystalline form of glycine. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 56,67, 2008. [source] The determination of aflatoxins in spices by immunoaffinity column extraction using HPLCINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2005Cavit Bircan Summary Seventy-five samples of different spices marketed in Turkey were purchased from bazaars, herbal shops and supermarkets. Equal amounts of paprika, chilli, black peppers and cumin were purchased and used to test and compare the amount of aflatoxin contamination. Two different analytical methods were examined for their efficacy by adding a known amount of aflatoxin to the blank samples of paprika. Twenty-seven paprika, all the chilli powder and four ground black pepper samples were contaminated with aflatoxin B1 in the range of 0.5,116.4, 1.6,80.4 and 0.3,1.2 ,g kg,1 respectively. Twenty-three (30%) paprika and chilli powder samples were above the regulatory limits used in the European Union. No aflatoxin contamination was detected in the cumin samples at a detection limit of 0.2 ,g kg,1. [source] Cation distribution in spinel (Mn,Co,Cr)3O4 at room temperatureJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2010A. Purwanto As part of a study of the long-term operation of solid-oxide fuel cells, three (Mn,Co,Cr)3O4 samples have been synthesized and characterized. X-ray and neutron diffraction patterns from the powder samples at room temperature were measured and the data were co-refined. The neutron data were indispensible in locating Mn, Co and Cr within the crystallographic unit cell with their respective atomic occupancies. Two of these samples have been identified as cubic Mn0.76Co0.58Cr1.66O4 and Mn1.28Co1.72O4. The third is a two-phase sample containing cubic Mn1.66Co1.34O4 and tetragonal Mn2.05Co0.91O4 in a 59.1,(6):40.9,(6)% mass fraction ratio. Cr, which might be introduced from reaction with chromia during oxidation of interconnect materials, exhibits a preference for the octahedral site rather than the tetrahedral site. Without Cr, Mn dominates the octahedral site. [source] In situ high-temperature powder diffraction study of reversible phase transitions in decagonal Al71.2Co12.8Ni16JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2003Christian Soltmann This experimental work is aimed at confirming and broadening findings of former investigations into the type I,S1 phase transition in Al,Co,Ni quasicrystals. In situ high-temperature synchrotron radiation measurements were carried out on Al71.2Co12.8Ni16 powder samples. The cell parameters were precisely determined at various temperatures in the range 290,1110,K. The data provided a new extended insight into the thermal expansion of Al71.2Co12.8Ni16 and into fundamental properties of the phase transition. [source] Parallel-beam X-ray diffractometry using X-ray guide tubesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2000Toyoko Yamanoi A parallel-beam X-ray diffraction geometry using X-ray guide tubes is proposed to eliminate preferred-orientation effects in powder X-ray diffraction (XRD) patterns and for new applications of XRD. A bundle of X-ray guide tubes (polycapillaries) is used to provide an intense quasi-parallel (approximately 0.2° divergence) and large-diameter (approximately 20,mm) beam of X-rays needed for parallel-beam diffractometry. Mica and silicon particles were agitated inside a cylindrical chamber by a steady flow of N2 gas so that they were randomly oriented. The quasi-parallel incident X-ray beam passed through the cloud of floating particles. The diffracted X-rays were detected using a standard 2, diffractometer. The integrated intensities observed agree well with those calculated from the known model of the crystal structure. This result demonstrates that this type of diffractometry is capable of avoiding preferred-orientation effects and of collecting XRD data for moving powder samples. [source] Synthesis and characterization of polyaniline films using Fenton reagentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008M. M. Ayad Abstract The chemical oxidation of aniline to form polyaniline (PANI) films and powder samples was made using Fenton reagent as an oxidizing agent in aqueous sulfuric acid medium. The PANI films were monitored by using the quartz crystal microbalance and the electronic absorption techniques. The optimum concentration was determined and the results were justified by measuring the UV,vis absorption spectra for the in situ PANI films. The conductivity for the PANI films and powder samples, prepared in different conditions, was measured. Also, the IR spectra, X-ray and the thermogravimetric analysis for the PANI powder formed in the bulk were measured and compared with the polymer prepared using ammonium peroxydisulfate. A preliminary investigation to the dielectric properties of the polymer powder was measured and discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A comparison of EDI with solvent-free MALDI and LDI for the analysis of organic pigmentsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2008Ichiro Kudaka Abstract To evaluate the applicability of EDI to material analysis as a new ionization method, a comparison of EDI with solvent-free matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) was made for the analysis of organic pigments, e.g. Pigment Yellow 93, Pigment Yellow 180, and Pigment Green 36, as test samples, which are poorly soluble in standard solvents. In EDI, the samples were prepared in two ways: deposition of suspended samples in appropriate solvents and dried on the substrate, and the direct deposition of the powder samples on the substrate. No matrices were used. Both sample preparation methods gave similar mass spectra. Equally strong signals of [M + H]+ and [M , H], ions were observed with some fragment ions for azo pigments in the respective positive or negative mode of operation. For the powder sample of the phthalocyanine pigment PG36, M+, and [M + H]+ in the positive mode and M,, in the negative mode of operation were observed as major ions. Positive-mode, solvent-free MALDI gave M+, [M + H]+ and [M + Na]+ and negative mode gave [M , H], depending on the sample preparation. As solvent-free MALDI, EDI was also found to be an easy-to-operate, versatile method for the samples as received. Copyright © 2008 John Wiley & Sons, Ltd. [source] A novel method for deriving true density of pharmaceutical solids including hydrates and water-containing powdersJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2004Changquan (Calvin) Sun Abstract True density is commonly measured using helium pycnometry. However, most water-containing powders, for example, hydrates, amorphous drugs and excipients, and most tablet formulations, release water when exposed to a dry helium atmosphere. Because released water brings significant errors to the measured true density and drying alters the nature of water-containing solids, the helium pycnometry is not suitable for those substances. To overcome this problem, a novel method has been developed to accurately calculate powder true density from compaction data. No drying treatment of powder samples is required. Consequently, the true density thus obtained is relevant to tableting characterization studies because no alteration to the solid is induced by drying. This method involves nonlinear regression of compaction pressure-tablet density data based on a modified Heckel equation. When true density values of water-free powders derived by this novel method were plotted against values measured using pycnometry, a regression line with slope close to unity and intercept close to zero was obtained. Thus, the validity of this method was supported. Using this new method, it was further demonstrated that helium pycnometry always overestimates true densities of water containing powders, for example, hydrates, microcrystalline cellulose (MCC), and tablet formulations. The calculated true densities of powders were the same for different particle shapes and sizes of each material. This further suggests that true density values calculated using this novel method are characteristic of given materials and independent of particulate properties. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:646,653, 2004 [source] Validated liquid chromatographic method for quantitative determination of allicin in garlic powder and tabletsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2007Marta de Diego Abstract In the present study, an RP high performance liquid chromatographic method was developed and validated for the determination of allicin in garlic powder and tablets. Chromatographic separation was carried out on an RP-18e column (125 mm×4 mm), using a mobile phase, consisting of methanol,water (50:50 v/v), at a flow rate of 0.5 mL/min and UV detection at 220 nm. Ethylparaben was used as the internal standard. The assay was linear for allicin concentrations of 5.0,60.0 ,g/mL. The RSD for precision was <6.14%. The accuracy was above 89.11%. The detection and quantification limits were 0.27 and 0.81 ,g/mL, respectively. This method was used to quantify allicin in garlic powder samples. The results showed that the method described here is useful for the determination of allicin in garlic powder and tablets. [source] Facilities for high-pressure research with the diamond anvil cell at GSECARSJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2005Guoyin Shen An overview of facilities for high-pressure research with the diamond anvil cell (DAC) at the GeoSoilEnviroCARS (GSECARS) sector at the Advanced Photon Source (Argonne, Illinois) is presented. There are three operational experimental stations (13-ID-C, 13-ID-D and 13-BM-D) where DAC instrumentation is installed for various types of experiments at high pressure and extreme temperature conditions. A fourth station (13-BM-C) is under construction and will be operational in 2006. While most X-ray diffraction experiments have been undertaken with powder samples so far, there is a growing demand for single-crystal diffraction (SCD) at high pressure. As one of the principal components at GSECARS, SCD is currently under rapid development. Other relevant techniques have also been developed for obtaining complementary information from powder or single-crystal samples at high pressure. For example, an on-line Brillouin system is installed and operational at 13-BM-D for acoustic velocity and single-crystal elasticity determinations. In addition, various X-ray spectroscopy techniques (e.g. X-ray emission and X-ray Raman) are employed for measuring electronic and magnetic properties. Future developments are discussed with the DAC program at GSECARS. [source] Specimen charging in X-ray absorption spectroscopy: correction of total electron yield data from stabilized zirconia in the energy range 250,915,eVJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2005Dimitrios Vlachos The effects of specimen charging on X-ray absorption spectroscopy using total electron yield have been investigated using powder samples of zirconia stabilized by a range of oxides. The stabilized zirconia powder was mixed with graphite to minimize the charging but significant modifications of the intensities of features in the X-ray absorption near-edge fine structure (XANES) still occurred. The time dependence of the charging was measured experimentally using a time scan, and an algorithm was developed to use this measured time dependence to correct the effects of the charging. The algorithm assumes that the system approaches the equilibrium state by an exponential decay. The corrected XANES show improved agreement with the electron energy-loss near-edge fine structure obtained from the same samples. [source] Comprehensive Linkage of Defect and Phase Equilibria through Ferroelectric Transition Behavior in BaTiO3 -Based Dielectrics: Part 1.JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Defect Energies Under Ambient Air Conditions Defect and phase equilibria have been investigated via the ferroelectric phase transition behavior of pure and equilibrated nonstoichiometric BaTiO3 powder samples. Through fabricating the BaTiO3 materials under highly controlled conditions to preserve the equilibrium conditions with respect to Ba/Ti ratio, annealing temperature (T), and oxygen partial pressure (PO2), systematic variations in the phase transition temperature can be noted with respect to Ba/Ti ratio and T. From the data extracted, we can then determine solubility limits. Equilibrating the defect reactions at the solubility limits provides a direct approach to identify and calculate the defect energetics. The phase transition temperature decreased with increasing concentration of the TiO2 partial-Schottky defects (BaTi1,,O3,2,) and the BaO partial-Schottky defects (Ba1,,TiO3,,), and showed discontinuous changes in the two-phase region. The formation enthalpy and entropy for the partial-Schottky defect reactions was evaluated to be 2.32±0.1 eV and 10.15±0.7 kB for the BaO partial-Schottky defect, and 2.89±0.1 eV and 8.0±1.5 kB for the TiO2 partial-Schottky defects equilibrated under air annealing conditions. [source] Sorption and Diffusion of Propylene and Ethylene in Heterophasic Polypropylene CopolymersMACROMOLECULAR SYMPOSIA, Issue 1 2007Michael Bartke Abstract Summary: Sorption experiments of ethylene and propylene in different polypropylene powder samples, both homopolymer and heterophasic copolymers with different rubber content, have been carried out in a high-pressure magnetic suspension balance at 10 bars pressure and 70,°C. The gross solubilities measured can be well correlated with the rubber content of the polymer samples. Solubility of ethylene and propylene in the rubber phase differ from solubility in the amorphous fraction of the homopolymer, especially the concentration ratio of propylene to ethylene differs significantly between rubber phase and amorphous fraction of the homopolymer. From the slope of monomer uptake, information on kinetics of mass-transfer can be gained. No significant differences were observed in terms of mass-transfer for ethylene and propylene. With increasing rubber content, effective diffusion coefficients increased slightly. By combined sorption studies with powder samples and compressed films, information about both effective diffusion coefficients and the effective length scale of diffusion could be gained. It could be shown, that the particle radius is not the characteristic length of diffusion in the studied powder samples. Mass transfer of nearly all samples could be described by a constant diffusion length of 120 to 130 µm, independently on particle size. This indicates that the effective scale of diffusion in polymer particles is in between microparticle and macroparticle scale used in classical particle modeling. [source] Physical adsorption vs. chemical binding of undecylenic acid on porous silicon surface: a comparative study of differently functionalized materialsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2009E. Pastor Abstract To imply miscibility to porous silicon (PSi) used for biomedical purposes a number of functionalization methods are employed. In order to distinguish between a non-specific surfactant-like interaction (physical sorption) and chemical binding of unsaturated chemicals (undecylenic acid, UD) to H-terminated PSi surface we studied the two differently treated materials. Differential scanning calorimetry (DSC) and thermogravimetry (TGA), BET and FTIR measurements were performed with the PSi powder samples (n+ doped). Changes in surface area, weight loss, calorific effect and chemical composition that accompanied the thermal treatment have shown that the physisorbed UD molecules undergo a chemical process (binding) with the Si-Hx surface groups at about 150 °C in both, N2 inert atmosphere and in a synthetic air, oxidative atmosphere. Controlled conversion of physically sorbed molecules to the chemically attached ones is discussed with respect to methods of surface modification of PSi materials for increasing their biocompatibility. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of nitrogen insertion on the magnetic and structural properties of Sm2,xGdxFe17 alloys (0 , x , 2)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2006M. S. Ben Kraiem Abstract The effect of nitrogen insertion on the structural and magnetic properties of Sm2,xGdxFe17Ny compounds (x = 0-2) has been investigated. X-ray diffraction patterns at room temperature show that all our synthesized samples are single phase and crystallize in the rhombohedral Th2Zn17 -type structure with very small amount of impurity. Nitrogen insertion leads to a monotonic increase in the unit cell volume, it leads also to an increase in the Curie temperature Tc from 425 K for SmGdFe17 to 760 K for SmGdFe17N3. Moreover, the nitrogen insertion increases the saturated magnetization Ms. Ms increases from 17.9 µB/mole for SmGdFe17 to 32.7 µB/mole for SmGdFe17N3. X-ray diffraction measurements on magnetically aligned powder samples of Sm2,xGdxFe17Ny reveal a change in the easy magnetization direction from planar before nitrogen insertion to the c-axis after nitrogen insertion. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On the possibility of using polycrystalline material in the development of structure-based generic assaysACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2009Marc Allaire The discovery of ligands that bind specifically to a targeted protein benefits from the development of generic assays for high-throughput screening of a library of chemicals. Protein powder diffraction (PPD) has been proposed as a potential method for use as a structure-based assay for high-throughput screening applications. Building on this effort, powder samples of bound/unbound states of soluble hen-egg white lysozyme precipitated with sodium chloride were compared. The correlation coefficients calculated between the raw diffraction profiles were consistent with the known binding properties of the ligands and suggested that the PPD approach can be used even prior to a full description using stereochemically restrained Rietveld refinement. [source] Fluoride content of powdered infant formula meets Australian Food Safety StandardsAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 6 2009Helen Clifford Abstract Objectives: To identify the fluoride content of powdered formula for infants 0-12 months in products available from Brisbane stores in 2006/07 and compare this with the fluoride content of infant formula products available in Australia 10 years earlier. Methods: A range of available infant formula powders were collected from major supermarkets and chemists in Brisbane, Queensland. The fluoride levels in infant formula powder samples were determined using a modification of the micro-diffusion method of Silva and Reynolds1 utilising perchloric acid and silver sulphate and measured with an ion selective (fluoride) electrode/meter. Fluoride content both prior to and after reconstitution, as well as estimated daily intake according to age was calculated. Results: Formula samples contained an average of 0.49 ,g F/g of powder (range 0.24,0.92 ,g F/g). After reconstitution with water containing 0mg/L fluoride, the fluoride content averaged 7.09,g F/100mL (range 3.367,22.72 ,g F/100mL). Estimated infant fluoride intakes ranged from 0.0039 mg/kg/day for a 6-12 month old infant when reconstituting milk-based formula with non-fluoridated water (0 mg/L), to 0.1735 mg/kg/day for a 0-3 month old infant when reconstituting soy-based formula with fluoridated water (1.0 mg/L). Conclusions: Infant formula powders contain lower levels of fluoride than previously found in Australia in 1996. Implications: This confirms that infants consume only a small amount of fluoride from milk-based powdered infant formula. Although soy-based infant formulas contain more fluoride than milk-based products, the levels still comply with national food standards. [source] ChemInform Abstract: Iodine as an Oxidant in the Topotactic Deintercalation of Interstitial Iron in Fe1+xTe.CHEMINFORM, Issue 43 2010Efrain E. Rodriguez Abstract The interstitial iron of Fe1+xTe is deintercalated from both single crystal and powder samples by a low temperature reaction with iodine (sealed quartz ampule, 300 °C, 18 h). [source] | |||||||||||||||||||