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Reference Materials (reference + material)

Distribution by Scientific Domains
Earth and Environmental Science38%
Chemistry37%
Polymers and Materials Science6%
Life Sciences6%
Medical Sciences4%
Humanities and Social Sciences3%
3 Other Domains6%

Kinds of Reference Materials

  • certified reference material
    		•
  • standard reference material
    		•

    Selected Abstracts

    Toxicity assessment of reference and natural freshwater sediments with the LuminoTox assay

    ENVIRONMENTAL TOXICOLOGY, Issue 4 2006
    P. M. Dellamatrice
    Abstract We examined the possibility of adapting the LuminoTox, a recently-commercialized bioanalytical testing procedure initially developed for aqueous samples, to assess the toxic potential of sediments. This portable fluorescent biosensor uses photosynthetic enzyme complexes (PECs) to rapidly measure photosynthetic efficiency. LuminoTox testing of 14 CRM (Certified Reference Material) sediments was first undertaken with (1) a "solid phase assay" (Lum-SPA) in which PECs are in intimate contact with sediment slurries for a 15 min exposure period and (2) an elutriate assay (Lum-ELU) in which PECs are exposed for 15 min to sediment water elutriates. CRM sediment toxicity data were then compared with those generated with the Microtox Solid Phase Assay (Mic-SPA). A significant correlation (P < 0.05) was shown to exist between Lum-SPA and Mic-SPA, indicating that both tests display a similar toxicity response pattern for CRM sediments having differing contaminant profiles. The sediment elutriate Lum-ELU assay displayed toxicity responses (i.e. measurable IC20s) for eight of the 14 CRM sediments, suggesting that it is capable of determining the presence of sediment contaminants that are readily soluble in an aqueous elutriate. Lum-SPA and Mic-SPA bioassays were further conducted on 12 natural freshwater sediments and their toxicity responses were more weakly, yet significantly, correlated. Finally, Lum-SPA testing undertaken with increasing mixtures of kaolin clay confirmed that its toxicity responses, in a manner similar to those reported for the Mic-SPA assay, are also subject to the influence of grain size. While further studies will be required to more fully understand the relationship between Lum-SPA assay responses and the physicochemical makeup of sediments (e.g., grain size, combined presence of natural and anthropogenic contaminants), these preliminary results suggest that LuminoTox testing could be a useful screen to assess the toxic potential of solid media. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 395,402, 2006. [source]

    Single Laboratory Method Performance Evaluation for the Analysis of Total Food Folate by Trienzyme Extraction and Microplate Assay

    JOURNAL OF FOOD SCIENCE, Issue 5 2007
    L. Chen
    ABSTRACT:, Single laboratory method performance parameters, including the calibration curve, accuracy, recovery, precision, limit of detection (LOD), and limit of quantification (LOQ), were evaluated for the analysis of total food folate by the trienzyme extraction and microplate assay with Lactobacillus casei subsp. rhamnosus. Standard Reference Material (SRM) 1546 (meat homogenate), SRM 2383 (baby food composite), SRM 1846 (infant formula), Certified Reference Material (CRM) 121 (wholemeal flour), and CRM 485 (mixed vegetables), representing a broad selection of food matrices, were used to evaluate the performance of the method. A generated 4-parameter logistic equation of the calibration curve was y= (0.0705 , 1.0396)/(1 + (x/0.0165) 1.3072) + 1.0396 (P < 0.0001). The test of parallelism demonstrated that matrix components in the food extracts did not affect the accuracy. Measured values of the SRMs and CRMs were within their certified or reference values. Recoveries for all reference materials met the requirements of the AOAC guidelines for single laboratory validation. Precision measured as repeatability, including simultaneous and consecutive replicates for each SRM and CRM, met the Horwitz criterion. LOD and LOQ values were 0.3 and 0.6 ,g/100 g, respectively. The results showed that trienzyme digestion using ,-amylase, PronaseR, and conjugase from chicken pancreas coupled with a 96-well microplate assay provided a highly accurate, reproducible, and sensitive method for the determination of folate in a variety of foods. [source]

    Isotopic metrology of carbon dioxide.

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2003

    We report a pilot study of high-precision differential isotope ratio measurements made on replicate samples of pure carbon dioxide using three instruments of identical manufacture. Measurement protocols were designed to explore the effects of sample size, ion source conductance, and inlet changeover equilibration time on the raw measurements. Our goal was better understanding of factors that influence these measurements in order to establish procedures for highly reproducible and accurate determinations of Reference Material (RM) isotopic compositions. Evaluation and modeling of reported data illuminated effects consistent with two instrumental memory sources,one short-lived (t½,,,10 s) and the other long-lived (t½,,,6,10,min), uncompensated by normal background measurements,that can significantly influence measurements made by the dual inlet method. These biases, proportional to the difference in isotopic compositions between the measured sample and reference gases, decrease in magnitude with increasing sample size, source conductance, and equilibration time. We observed biases as high as 0.1, per 10, difference between sample and reference gases. These memory sources may be responsible for measured ,13C values of RMs generally being highly reproducible within any single laboratory but less reproducible among independent laboratories. The magnitude of the bias is consistent with the ranges of ,13C values reported in prior laboratory intercomparisons. Uncertainties are most likely due to high and variable long-lived memory among the instruments tested. Published in 2003 by John Wiley & Sons, Ltd. [source]

    U-Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma,Mass Spectrometry Coupled with Frequency Quintupled Nd-YAG (, = 213 nm) Laser Ablation System: Comparison with LA-ICP-MS Zircon Analyses with a NIST Glass Reference Material

    RESOURCE GEOLOGY, Issue 2 2008
    Yuji Orihashi
    Abstract This paper evaluates the analytical precision, accuracy and long-term reliability of the U-Pb age data obtained using inductively coupled plasma,mass spectrometry (ICP-MS) with a frequency quintupled Nd-YAG (, = 213nm) laser ablation system. The U-Pb age data for seven standard zircons of various ages, from 28 Ma to 2400 Ma (FCT, SL13, 91500, AS3, FC1, QGNG and PMA7) were obtained with an ablation pit size of 30 ,m diameter. For 207Pb/206Pb ratio measurement, the mean isotopic ratio obtained on National Institute of Standards and Technology (NIST) SRM610 over 4 months was 0.9105 ± 0.0014 (n = 280, 95% confidence), which agrees well with the published value of 0.9096. The time-profile of Pb/U ratios during single spot ablation showed no significant difference in shape from NIST SRM610 and 91500 zircon standards. These results encouraged the use of the glass standard as a calibration standard for the Pb/U ratio determination for zircons with shorter wavelength (, = 213 nm) laser ablation. But 206Pb/238U and 207Pb/235U ages obtained by this method for seven zircon standards are systematically younger than the published U-Pb ages obtained by both isotope dilution,thermal ionization mass spectrometry (ID-TIMS) and sensitive high-resolution ion-microprobe (SHRIMP). Greater discrepancies (3,4% younger ages) were found for the 206Pb/238U ages for SL13, AS3 and 91500 zircons. The origin of the differences could be heterogeneity in Pb/U ratio on SRM610 between the different disks, but a matrix effect accuracy either in the ICP ion source or in the ablation-transport processes of the sample aerosols cannot be neglected. When the 206Pb/238U (= 0.2302) newly defined in the present study is used, the measured 206Pb/238U and 207Pb/235U ages for the seven zircon standards are in good agreement with those from ID-TIMS and SHRIMP within ±2%. This suggests that SRM610 glass standard is suitable for ICP-MS with laser ablation sampling (LA-ICP-MS) zircon analysis, but it is necessary to determine the correction factor for 206Pb/238U by measuring several zircon standards in individual laboratories. [source]

    Rare Earth Element Concentrations in the Natural Water Reference Materials (NRCC) NASS-5, CASS-4 and SLEW-3

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2007
    Michael G. Lawrence
    terres rares; yttrium; pré-concentration; ICP-MS; matériaux de référence du NRCC The rare earth element and yttrium concentrations of the NRCC reference materials North Atlantic Surface seawater, NASS-5; Coastal Atlantic Surface Seawater, CASS-4; and the estuarine water, SLEW-3 have been precisely determined by ICP-MS after ca. 1:8 preconcentration following a triple chelation using HDEHP (phosphoric acid 2-ethylhexyl ester -mono and di ester mixture) in heptane, and back extraction in nitric acid. We propose reference values with uncertainties for all naturally occurring lanthanides and yttrium. Les concentrations en terres rares et en yttrium des matériaux de référence suivants (du NRCC): l'eau de surface de l'Atlantique Nord NASS-5, l'eau de surface de l'Atlantique Côtier CASS-4 et l'eau d'estuaire SLEW-3 ont été déterminées précisément par ICP-MS après concentration d'un facteur 1 : 8 environ, suivie d'une triple chélation avec de l'HDEHP (mixture d'acide phosphorique 2-ethylhexyl ester - mono et di ester) dans de l'heptane et une extraction inverse en acide nitrique. Nous proposons des valeurs de référence avec leur incertitude pour toutes les terres rares naturelles et l'yttrium. [source]

    Three Secondary Reference Materials for Lithium Isotope Measurements: Li7-N, Li6-N and LiCl-N Solutions

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2007
    Jean Carignan
    matériaux de référence; isotopes de Li; solutions de Li; QUAD-ICP-MS; MC-ICP-MS The CRPG (Nancy, France) has prepared secondary reference materials for Li isotope measurements by mixing 7Li or 6Li spikes and either L-SVEC or IRMM-016 certified reference materials to produce solutions having a known Li concentration and isotopic composition. The Li7-N and Li6-N solution samples (1.5 mol l,1 HNO3) have nominal ,7Li isotopic compositions of 30.1, and -9.7, respectively relative to L-SVEC and concentrations of 100 mg l,1. Repeated measurement of these samples using the QUAD-ICP-MS at the CRPG yielded ,7Li of 30.4 ± 1.1, (n = 13) and -8.9 ± 0.9, (n = 9) at the 2s level of confidence. An additional LiCl-N solution was measured and yielded a delta value of 9.5 ± 0.6, (n = 3). Identical results were obtained at the BRGM (Orléans, France) from determinations performed with a Neptune MC-ICP-MS (30.2 ± 0.3,, n = 89 for the Li7-N, -8.0 ± 0.3,, n = 38 for the Li6-N and 10.1 ± 0.2,, n = 46 for LiCl-N at the 2s level of confidence). The deviation of measured composition relative to the nominal value for the Li6-N solution might be explained by either contamination during preparation or an error during sample weighing. These secondary reference materials, previously passed through ion exchange resin or directly analysed, may be used for checking the accuracy of Li isotopic measurements over a range of almost 40, and will be available to the scientific community upon request to J. Carignan or N. Vigier, CRPG. Le CRPG (Nancy, France) a préparé des matériaux secondaires de référence pour l'analyse des isotopes du Li en mélangeant des spikes de 7Li ou 6Li avec les matériaux de référence certifiés L-SVEC ou IRMM-016, ceci afin de produire des solutions ayant des concentrations et compositions isotopiques de Li connues. Les solutions Li7-N et Li6-N (1.5 mol l,1 HNO3) ont des compositions isotopiques nominales de ,7Li, exprimées par rapport à L-SVEC, de 30.1, et de -9.7, respectivement, et des concentrations de 10 0 mg l,1. L'analyse répétée de ces solutions par QUAD-ICP-MS au CRPG donne des ,7Li de 30.4 ± 1.1, (n = 13) et -8.9 ± 0.9, (n = 9) avec une incertitude à 2s. Une solution additionnelle de LiCl-N a été analysée et a donné une valeur de delta de 9.5 ± 0.6, (n = 3). Des résultats identiques ont été obtenus au BRGM (Orléans, France) où les déterminations ont été effectuées sur le MC-ICP-MS Neptune (30.2 ± 0.3,, n = 89 pour Li7-N, -8.0 ± 0.3,, n = 38 pour Li6-N et 10.1 ± 0.2,, n = 46 pour LiCl-N, à 2s d'intervalle de confiance). Le biais entre les compositions mesurées et la valeur nominale, observé pour la solution Li6-N peut être expliqué par une contamination durant la préparation ou par une erreur durant la pesée. Ces matériaux secondaires de référence, préalablement passés sur résine échangeuse d'ions ou analysés directement, peuvent être utilisés pour vérifier la justesse des analyses isotopiques de Li sur une gamme de presque 40% et sont à la disposition de la communauté scientifique sur demande auprès de J. Carignan ou N. Vigier, CRPG. [source]

    Reference Materials in Geoanalytical Research -Review for 2004 and 2005

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 3 2006
    Klaus Peter Jochum
    This review gives an overview of the use and development of reference materials of geochemical and environmental interest in the literature of the years 2004 and 2005. In these years the performance of existing methods has been improved and new geochemical applications using new techniques have been developed. Accordingly, there was an increasing need for new reference materials, especially for in situ microanalysis and for precise stable isotope measurements. In addition, there was a notable trend for further characterisation of existing reference materials, mainly for the platinum-group elements. This review focuses on five topics: reference materials for platinum-group elements, reference glasses for in situ microanalysis, zircon reference materials, isotopic reference materials, and the development and certification of reference materials. [source]

    Determination of Ti, K, Sm and Gd Values in Geological Survey of Japan Reference Materials by Prompt Gamma Neutron Activation Analysis

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2006
    Takashi Sano
    activation neutronique et comptage gamma; GSJ; roches ignées; samarium gadolinium Prompt gamma neutron activation analysis was applied to the determination of the titanium, potassium, samarium and gadolinium contents of nine Geological Survey of Japan (GSJ) reference materials (JB-1, 1a, 2, 3; JA-1, 2, 3; JR-1, 2). Firstly, the values in JB-1 were determined by the standard addition method: pressed powder disks of JB-1 were used for neutron irradiation and gamma-ray measurements, after known quantities of standard reagents had been added. Secondly, the contents of eight other reference materials were determined by comparison methods using JB-1 as the comparative standard. The precision of analyses were obtained by replicate determinations on these samples. The relative standard deviation was generally less than 5%. For most samples, analysed values agreed well (< 5%) with the recommended values. L'analyse par activation neutronique et comptage des particules gamma rapide a été appliquée à la détermination des concentrations en titane, potassium, samarium et gadolinium de neuf matériaux de référence du Service Géologique du Japon (GSJ) : (JB-1, 1a, 2, 3; JA-1, 2, 3; JR-1, 2). Tout d'abord les teneurs dans JB-1 ont été déterminées par la technique de l'addition de standard : des pastilles de poudre compressée de JB-1 ont été irradiées par un flux neutronique puis la mesure des émissions gamma, a été effectuée après que des quantités connues de réactifs standards aient été ajoutées. Ensuite les teneurs dans les huit autres ont été déterminées en utilisant JB-1 comme standard de calibration. La précision des analyses a été déterminée en dupliquant les analyses de ces échantillons. Les déviations standard relatives étaient généralement de moins de 5%. Pour la plupart des échantillons les teneurs déterminées sont en bon accord (< 5%) avec les valeurs recommandées. [source]

    Precise/ Small Sample Size Determinations of Lithium Isotopic Compositions of Geological Reference Materials and Modern Seawater by MC-ICP-MS

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2004
    Alistair B. Jeffcoate
    composition isotopique de Li; matériaux de référence silicates; eau de mer; MC-ICP-MS; Li standard The Li isotope ratios of four international rock reference materials, USGS BHVO-2, GSJ JB-2, JG-2, JA-1 and modern seawater (Mediterranean, Pacific and North Atlantic) were determined using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). These reference materials of natural samples were chosen to span a considerable range in Li isotope ratios and cover several different matrices in order to provide a useful benchmark for future studies. Our new analytical technique achieves significantly higher precision and reproducibility (< ± O.3%o 2s) than previous methods, with the additional advantage of requiring very low sample masses of ca. 2 ng of Li. Les rapports isotopiques du Li de 4 matériaux de référence, de provenance Internationale, BHVO-2, JB-2, JG-2, JA-1 et d'eau de mer (Méditerranée, Pacifique et Atlantique Nord) ont été déterminés par MC-ICP-MS (spectrométrie de masse avec source à plasma induit à multicollection). Ces matériaux de référence naturels ont été choisis car ils balaient un large champ des rapports isotopiques du Lithium et couvrent différentes matrices afin de fournir un point de repère utile pour les études futures. Notre nouvelle technique analytique permet d'atteindre une précision et une reproductibilité (< ± 0.3%. 2s) nettement supérieures à celles des méthodes précédemment utilisées et présente I'avantage de pouvoir travailler avec des échantillons de petite masse, , 2 ng de Li. [source]

    Calcium Isotopic Composition of Various Reference Materials and Seawater

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2003
    Dorothee Hippler
    composition isotopique du calcium; eau de mer; paléocéanographie; NIST SRM 915a A compilation of ,44/40Ca (,44/40Ca) data sets of different calcium reference materials is presented, based on measurements in three different laboratories (Institute of Geological Sciences, Bern; Centre de Géochimie de la Surface, Strasbourg; GEOMAR, Kiel) to support the establishment of a calcium isotope reference standard. Samples include a series of international and internal Ca reference materials, including NIST SRM 915a, seawater, two calcium carbonates and a CaF2 reference sample. The deviations in ,44/40Ca for selected pairs of reference samples have been defined and are consistent within statistical uncertainties in all three laboratories. Emphasis has been placed on characterising both NIST SRM 915a as an internationally available high purity Ca reference sample and seawater as representative of an important and widely available geological reservoir. The difference between ,44/40Ca of NIST SRM 915a and seawater is defined as -1.88 O.O4%o (,44/42CaNISTSRM915a/Sw= -0.94 0.07%o). The conversion of values referenced to NIST SRM 915a to seawater can be described by the simplified equation ,44/40CaSa/Sw=,44/40CaSa/NIST SRM 915a - 1.88 (,44/42CaSa/Sw=,44/42CaSa/NIST SRM 915a - 0.94). We propose the use of NIST SRM 915a as general Ca isotope reference standard, with seawater being defined as the major reservoir with respect to oceanographic studies. On présente ici une compilation de données de ,44/40Ca (,44/42Ca) obtenues sur différents matériaux de référence, à partir d'analyses effectuées dans trois laboratoires (Institute of Geological Sciences, Berne; Centre de Géochimie de la Surface, Strasbourg; GEOMAR, Kiel) dans le but de définir des matériaux standards de référence pour isotopie du calcium. Les échantillons comprenaient une série de matériaux standards, internes et internationaux, de référence pour le calcium, avec NIST SRM 915a, l'eau de mer, deux carbonates de calcium, et un échantillon de CaF2 de référence. Les déviations en ,44/40Ca pour des paires sélectionnées d'échantillons de référence ont été définies et sont en accord, compte tenu des incertitudes statistiques, entre les trois laboratoires. L'accent a été mis sur la nécessité de caractériser à la fois NIST SRM 915a, en tant que matériau de référence très pur, internationalement disponible, et l'eau de mer comme représentant d'un réservoir géologique très important et disponible partout. La différence entre les ,44/40Ca de NIST SRM 915a et de l'eau de mer est définie comme étant de -1.88 0.04%0,44/42CaNIST SRM 915a/Sw= -0.94 0.07%0). La conversion des données référencées par rapport à NIST SRM 915a à la référence -eau de mer- se fait selon l'équation simplifiée équation ,44/40CaSa/Sw=,44/40CaSa/NIST SRM 915a - 1.88 (,44/42Ca Sa/Sw=,44/42CaSa/NIST SRM 915a - 0.94). Nous proposons l'utilisation de NIST SRM 915a comme matériau standard de référence pour les isotopes de Ca, avec l'eau de mer comme réservoir majeur adapté aux études océanographiques. [source]

    Determination of Selenium Concentration in Sixty Five Reference Materials for Geochemical Analysis by GFAAS after Separation with Thiol Cotton

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2-3 2001
    Luc Marin
    sélénium; SAA four graphite; séparation; matériaux géologiques de référence; coton thiol Selenium has been determined in sixty five geological reference materials of different origins by graphite furnace atomic absorption spectrometry. Samples were decomposed with a mixture of nitric and hydrofluoric acids. Selenium was reduced to SeIV with hydrochloric acid, and then fixed and separated from the matrix on thiol cotton. After digestion of the thiol cotton in hot nitric acid, the Se concentration was measured using palladium and magnesium nitrates as a matrix modifier. The limit of determination was 0.02 ,g g,1, the precision of the results (relative standard deviation of 3 to 8 replicates) varied from 2.6 to 17.7% with an average of 7.9% in the range 0.02-42.7 ,g g,1 and was similar to the value obtained for synthetic samples. Our results are in good agreement with available literature values. Le sélénium a été dosé sur 65 standards géochimiques de référence de différentes provenances par spectrométrie d'absorption atomique avec four graphite. Les échantillons ont été mis en solution par une attaque acide HNO3 -HF. Le sélénium a été réduit en SeIV avec de l'acide chlorhydrique, fixé et séparé de la matrice sur du coton thiol. Après décomposition du coton thiol par chauffage avec de l'acide nitrique, les concentrations en sélénium ont été mesurées en utilisant du nitrate de palladium et de magnésium comme modificateur de matrice. La limite de détermination est de 0.02 ,g g,1, la précision des résultats (écart type relatif sur 3 à 8 mesures) pour les standards géochimiques varie de 2.6 à 17.7% avec une moyenne de 7.9% dans la game 0.02-42.7 ,g g,1et est comparable à celle obtenue pour des échantillons synthétiques. Nos résultats sont en bonne concordance avec les résultats déjà publiés dans la littérature. [source]

    The Use of Reference Materials: A Tutorial

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2001
    Jean S. Kane
    reference materials; certified reference materials; method validation; traceability of measurement; geochemical analysis Any review of the analytical literature shows that, while reference materials are routinely used in laboratories world-wide, not all uses follow ISO Guide 33 (1989), which outlines best practices. Analytical data quality can suffer as a result. This paper reviews the various uses that the geoanalytical community has made of reference materials from a historical perspective, and suggests improvements in practice that would more closely follow ISO Guide 33 recommendations. Un examen de la littérature dans le domaine analytique montre que, si les matériaux de référence sont utilisés en routine dans les laboratoires du monde entier, ces derniers ne suivent pas toujours les recommandations du guide ISO 33 (1989a), qui souligne les bonnes pratiques de laboratoire. La qualité des données analytiques peut alors en souffrir. Cet article passe en revue les différentes utilisations des matériaux de référence par la communauté de géoanalyse, ceci d'un point de vue historique, et suggère des améliorations de pratiques pour suivre au mieux les recommandations du guide ISO 33. [source]

    Preparation and Certification of High-Grade Gold Ore Reference Materials (GAu 19-22)

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2001
    Tiexin Gu
    materiau de référence certifié; gisement d 'or,GAu 19-22,IGGE,valeurs certifiées Two types of gold deposit with both good homogeneity and a high-grade of gold were selected to prepare four gold ore reference materials (GAu-19,GAu-20,GAu-21 and GAu-22) by the Institute of Geophysical and Geochemical Exploration (IGGE),China. Seven laboratories participated in the certification programme. Volumetric methods for GAu19-21 and atomic absorption spectrometry for GAu-22 were used for the homogeneity testing,the coefficient of variation being found to be less than 3%. After sample digestion and preconcentration,the samples were analysed by flame atomic absorption spectrometry (AAS),colorimetry,neutron activation analysis (NAA)and volumetric analysis. The certified values for the gold concentration in GAu19-22 are 18.3 ,g g -1, 32.3 ,g g -1, 53.0 ,g g -1 and 5.72 ,g g -1,respectively. Deux types de gisements d'or, présentant à la foisune bonne homogénéité et une teneur élevée en or, ont été sélectionnés par l'Institut d 'Exploration Géophysique et Géochimique de Chine (IGGE)afin de préparer quatre matériaux de référence pour l'or (GAu-19,GAu-20,GAu-21 et Gau-22). Sept laboratoires ont participé au programme de certification. Des méthodes volumétriques (GAu-19-21)et de spectrométrie par absorption atomique (GAu 22)ont été utilisées pour tester l'homogénéité de ces échantillons;les coefficients de variation se sont révélés inférieurs à 3%.Après la mise en solution et la préconcentration des échantillons,ceux-ci ont eté analysés par spectrométrie d 'absorption atomique (AAS), colorimétrie,activation neutronique (NAA)et analyse volumétrique.Les valeurs certifiées pour la concentration en or de GAu19-22 sont respectivement de 18.3 ,g.g -1,32.3 ,g g -1, 53.0 ,g g -1 et 5.72 ,g g -1. [source]

    Molybdenum Concentrations Measured in Eleven USGS Geochemical Reference Materials by Isotope Dilution Thermal Ionisation Mass Spectrometry

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2000
    Michael E. Wieser
    molybdène; dilution isotopique; spectrométrie de masse à; thermo-ionisation; matériaux de référence USGS Molybdenum concentrations in eleven USGS geochemical reference materials AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 and W-2 were measured by isotope dilution thermal ionisation mass spectrometry (ID-TIMS). In every case but one, the concentrations determined in this study were significantly lower than the current consensus values. Molybdenum concentrations determined by ID-TIMS are inherently more accurate and precisions may be up to an order of magnitude higher than those measured by other analytical techniques. Les concentrations en molybdène de onze matériaux géochimiques de référence de l'USGS, AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 et W-2, ont été mesurées par dilution isotopique et spectrométrie de masse à thermo-ionisation (ID-TIMS). Dans tous les cas sauf un, les concentrations déterminées dans cette étude sont nettement inférieures aux valeurs généralement admises. Les concentrations en molybdène déterminées par ID-TIMS sont par définition plus exactes et leur précision analytique peut tre améliorée d'un ordre de grandeur par rapport à celle déterminée par d'autres techniques analytiques. [source]

    Measurement of the ,34S value in methionine by double spike multi-collector thermal ionization mass spectrometry using Carius tube digestion,

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2010
    Jacqueline L. Mann
    Methionine is an essential amino acid and is the primary source of sulfur for humans. Using the double spike (33S- 36S) multi-collector thermal ionization mass spectrometry (MC-TIMS) technique, three sample bottles of a methionine material obtained from the Institute for Reference Materials and Measurements have been measured for ,34S and sulfur concentration. The mean ,34S value, relative to Vienna Canyon Diablo Troilite (VCDT), determined was 10.34,±,0.11, (n,=,9) with the uncertainty reported as expanded uncertainties (U). These ,34S measurements include a correction for blank which has been previously ignored in studies of sulfur isotopic composition. The sulfur concentrations for the three bottles range from 56 to 88,µg/g. The isotope composition and concentration results demonstrate the high accuracy and precision of the DS-MC-TIMS technique for measuring sulfur in methionine. Published in 2010 by John Wiley & Sons, Ltd. [source]

    Pliocene clays from Aegina (Greece): Reference material for chemical provenance studies on bronze age pottery from the Island

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2004
    Anno Hein
    Normally, the use of clays as reference materials in chemical provenance studies of ancient ceramics is complicated due to the original clay paste processing. The primary mixing and/or refining of raw materials during pottery production makes a straightforward comparison of archaeological ceramics with extant geological materials difficult if not impossible in many cases. However, in the case of Pliocene clays from Aegina (Greece), which were examined chemically and mineralogically and compared with Bronze Age pottery produced on the island, a successful exception can be presented. The chemical composition of a large group of Aeginetan pottery resembles the chemical composition of clays from a deposit in close vicinity to the main Bronze Age settlement of the island. Clays from specific outcrops exhibit considerable chemical and mineralogical homogeneity, and the suitability of those clays for pottery production apparently made substantial clay paste processing unnecessary. © 2004 Wiley Periodicals, Inc. [source]

    Metrological sharp shooting for plasma proteins and peptides: The need for reference materials for accurate measurements in clinical proteomics and in vitro diagnostics to generate reliable results

    PROTEOMICS - CLINICAL APPLICATIONS, Issue 9 2007
    Frank Vitzthum Dr.
    Abstract Reliable study results are necessary for the assessment of discoveries, including those from proteomics. Reliable study results are also crucial to increase the likelihood of making a successful choice of biomarker candidates for verification and subsequent validation studies, a current bottleneck for the transition to in vitro diagnostic (IVD). In this respect, a major need for improvement in proteomics appears to be accuracy of measurements, including both trueness and precision of measurement. Standardization and total quality management systems (TQMS) help to provide accurate measurements and reliable results. Reference materials are an essential part of standardization and TQMS in IVD and are crucial to provide metrological correct measurements and for the overall quality assurance process. In this article we give an overview on how reference materials are defined, prepared and what role they play in standardization and TQMS to support the generation of reliable results. We discuss how proteomics can support the establishment of reference materials and biomarker tests for IVD applications, how current reference materials used in IVD may be beneficially applied in proteomics, and we provide considerations on the establishment of reference materials specific for proteomics. For clarity, we solely focus on reference materials related to serum and plasma. [source]

    A Delphi survey of the views of adult male patients with personality disorders on psychoeducation and social problem-solving therapy

    CRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 5 2007
    Mary McMurran
    Background,Psychoeducation and social problem-solving therapy are treatment components that work well in tandem for offenders with personality disorders, hence it is worthwhile to maintain and improve their effectiveness. Aim,The aim was to seek patients' views of these therapies to contribute to their development. Method,A Delphi survey was conducted with all 12 male inpatients of a personality disorder hospital treatment unit. Results,Round 1 produced 30 statements for psychoeducation and 59 for social problem-solving therapy to be rated in Round 2. There was consensus at a level of 70% for all items. Both psychoeducation and social problem-solving therapies were viewed as useful by these patients. The men also suggested improvements in psychoeducation, including minimizing the delay between assessment and feedback, provision of reference material, preparation for the work and support afterwards. Areas identified for improvement in social problem-solving therapy included more frequent review of progress, greater consistency of delivery, eliciting problems more effectively, providing reference material, supporting patients in group work, and the development of an advanced therapy. Discussion,A Delphi approach to evaluation of therapies with the people receiving them is not only feasible but seems to offer a practical way of making useful clinical adjustments to the work. Further research with larger samples might usefully focus on whether such an approach enhances treatment compliance. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    The use of in vitro technologies coupled with high resolution accurate mass LC-MS for studying drug metabolism in equine drug surveillance

    DRUG TESTING AND ANALYSIS, Issue 1 2010
    James P. Scarth
    Abstract The detection of drug abuse in horseracing often requires knowledge of drug metabolism, especially if urine is the matrix of choice. In this study, equine liver/lung microsomes/S9 tissue fractions were used to study the phase I metabolism of eight drugs of relevance to equine drug surveillance (acepromazine, azaperone, celecoxib, fentanyl, fluphenazine, mepivacaine, methylphenidate and tripelennamine). In vitro samples were analyzed qualitatively alongside samples originating from in vivo administrations using LC-MS on a high resolution accurate mass Thermo Orbitrap Discovery instrument and by LC-MS/MS on an Applied Biosystems Sciex 5500 Q Trap. Using high resolution accurate mass full-scan analysis on the Orbitrap, the in vitro systems were found to generate at least the two most abundant phase I metabolites observed in vitro for all eight drugs studied. In the majority of cases, in vitro experiments were also able to generate the minor in vivo metabolites and sometimes metabolites that were only observed in vitro. More detailed analyses of fentanyl incubates using LC-MS/MS showed that it was possible to generate good quality spectra from the metabolites generated in vitro. These data support the suggestion of using in vitro incubates as metabolite reference material in place of in vivo post-administration samples in accordance with new qualitative identification guidelines in the 2009 International Laboratory Accreditation Cooperation-G7 (ILAC-G7) document. In summary, the in vitro and in vivo phase I metabolism results reported herein compare well and demonstrate the potential of in vitro studies to compliment, refine and reduce the existing equine in vivo paradigm. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Determination of Lead and Cadmium at Silver Electrode by Subtractive Anodic Stripping Voltammetry in Plant Materials Containing Tl

    ELECTROANALYSIS, Issue 9 2005
    Beata Krasnod, bska-Ostr
    Abstract Lead and cadmium have been determined by the subtractive anodic stripping voltammetry using the square-wave mode at a silver electrode without removal of oxygen. The samples containing large amount of thallium were collected from a highly contaminated region. The presence of thallium strongly affects the peak shape of Cd. The plant material digestion was performed with HNO3/HClO4 mixture using pressurised microwave decomposition. The proposed method used for the lead determination was validated by the inter-method comparison (ICP-MS). The cadmium determination was validated using certified reference material. The results obtained, supported by statistical tests, demonstrated the usefulness of the method for the lead determination in samples containing large amounts of Cd and Tl. It is important to note that Cd can only be quantified when the thallium concentration is much lower than that of cadmium. [source]

    Determination of iodine and bromine compounds in foodstuffs by CE-inductively coupled plasma MS

    ELECTROPHORESIS, Issue 22 2007
    Jing-Huan Chen
    Abstract A CE-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for iodine and bromine speciation analysis is described. Samples containing ionic iodine (I, and IO3,) and bromine (Br, and BrO3,) species are subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100). The separation has been achieved in a 50,cm length×75,,m id fused-silica capillary. The electrophoretic buffer used is 10,mmol/L Tris (pH,8.0), while the applied voltage is set at ,8,kV. Detection limits are 1 and 20,50,ng/mL for various I and Br compounds, respectively, based on peak height. The RSD of the peak areas for seven injections of 0.1,,g/mL I,, IO3, and 1,,g/mL Br,, BrO3, mixture is in the range of 3,5%. This method has been applied to determine various iodine and bromine species in NIST SRM 1573a Tomato Leaves reference material and a salt and seaweed samples obtained locally. A microwave-assisted extraction method is used for the extraction of these compounds. Over 87% of the total iodine and 83% of the total bromine are extracted using a 10% m/v tetramethylammonium hydroxide (TMAH) solution in a focused microwave field within a period of 10,min. The spike recoveries are in the range of 94,105% for all the determinations. The major species of iodine and bromine in tomato leaves, salt, and seaweed are Br,, IO3,, I,, and Br,, respectively. [source]

    Impact of changes in analytical techniques for the measurement of polychlorinated biphenyls and organochlorine pesticides on temporal trends in herring gull eggs

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010
    Shane R. de Solla
    Abstract Changes in analytical approaches during the tenure of monitoring programs for organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) may affect estimates of temporal trends. We used an in-house reference material to create multiplication factors to adjust the estimates of OC pesticides and PCBs (Aroclor equivalents) in Great Lake herring gull eggs analyzed using electron capture detection (1987,1997) to be more equivalent to estimates using mass spectrometric detection (1998,2005) as well as accompanying differences in analytical procedures. We examined temporal trends in contaminant concentrations in herring gull eggs using change point regressions, to determine whether significant changes in long-term trends were associated with analytical methodology. The highest frequency of change point occurrences shifted from 1997 (when analytical methodology was altered) to 2003 after data adjustment. The explanatory power (r2) of the regressions was lower after adjustment, although only marginally so (mean r2 difference,=,0.04). The initial rates of decline before change points in contaminant concentrations were generally slower after the data adjustment, but after any change points the declines were not significantly different. The regression models did not change for 83.3% of the cases. The effects on the interpretation of long-term temporal trends in herring gull eggs, although not negligible, were minor relative to the magnitude of the temporal changes. Environ. Toxicol. Chem. 2010;29:1476,1483. © 2010 SETAC [source]

    Theoretical framework for the distribution of trace metals among the operationally defined speciation phases of a sediment

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2001
    René A. Nome
    Abstract The use of a model based on Langmuir's isotherm to evaluate the metal associated with separate geochemical phases of a sediment is proposed and its validity tested with sediments of certified composition. The model takes into account a standard procedure for a certified reference material (CRM601), which defines, experimentally, a set of sequential extractions that divide the sediment into four operational fractions. The derived equations allow the treatment of data from sediment of Flumendosa Lake, Italy, and certified material CRM601 and also allow the computation of corrected concentrations, i.e., the metal affinities for each fraction. Experimental values for Ni show its low sensitivity and an equal distribution among different phases, which suggests a similar adsorption mechanism in all cases. In the case of Cd, the corrected concentration in the Fe/Mn oxide phase is nine times higher than for the residual fraction. For sediment of the Bèsos River, Spain, results show the percentage distribution of Ni over different fractions. Affinity values for Ni on a Flumendosa Lake sediment have also been calculated. The present model is simple to apply and shows satisfactory agreement with experimental data. [source]

    WDX Studies on Ceramic Diffusion Barrier Layers of Metal Supported SOECs

    FUEL CELLS, Issue 6 2009
    D. Wiedenmann
    Abstract Solid oxide electrolyser cells (SOECs) have great potential for efficient and economical production of hydrogen fuel. Element diffusion between the Ni-cermet electrode and the metal substrate of metal supported cells (MSC) is a known problem in fuel cell and electrolysis technology. In order to hinder this unintentional mass transport, different ceramic diffusion barrier layers (DBLs) are included in recent cell design concepts. This paper is based on wavelength dispersive X-ray fluorescence investigations of different SOEC and focuses on Fe, Cr and Ni diffusion between the metal grains of the cathode and the metal substrate. Due to the low detection limits and therefore high analytical sensitivity, wavelength dispersive electron probe microanalysis (EPMA) provides a precise method to determine element distribution, absolute element concentration and changes between the reference material and aged cells on a microstructural level by element mappings and concentration profiles. The results of this work show considerable concentration gradients in the metal grains caused by mass exchange during cell operation. Diffusion can be inhibited significantly by integrating different ceramic DBLs of doped LaCrO3 -type or doped LaMnO3 -type perovskite, either by vacuum plasma spraying (VPS) or physical vapour deposition technique (PVD). [source]

    Composition-Induced Variations in SIMS Instrumental Mass Fractionation during Boron Isotope Ratio Measurements of Silicate Glasses

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2008
    Martin Rosner
    isotopes du bore; SIMS; effet de matrice; matériaux vitreux de référence; fractionnement de masse instrumental An analytical artefact is reported here related to differences in instrumental mass fractionation between NIST SRM glasses and natural geological glasses during SIMS boron isotope determinations. The data presented demonstrated an average 3.4, difference between the NIST glasses and natural basaltic to rhyolitic glasses mainly in terms of their sputtering-induced fractionation of boron isotopes. As no matrix effect was found among basaltic to rhyolitic glasses, instrumental mass fractionation of most natural glass samples can be corrected by using appropriate glass reference materials. In order to confirm the existence of the compositionally induced variations in boron SIMS instrumental mass bias, the observed offset in SIMS instrumental mass bias has been independently reproduced in two laboratories and the phenomenon has been found to be stable over a period of more than one year. This study highlights the need for a close match between the chemical composition of the reference material and the samples being investigated. Nous montrons l'existence d'un artefact analytique reliéà différents fractionnements de masse instrumentaux, observés sur les verres NIST SRM et des verres naturels durant des mesures des isotopes de bore par SIMS. Les données montrent une différence d'environ 3.4, entre les verres NIST et les verres naturels, de composition variant de basaltique à rhyolitique, en termes de fractionnement des isotopes du bore principalement induit par le phénomène de dispersion. Comme aucun effet de matrice n'a été observé entre les verres basaltiques et les verres rhyolitiques, le fractionnement de masse instrumental de la plupart des verres naturels peut être corrigé en utilisant des verres de références appropriés. Dans le but de confirmer l'existence de biais de masse liéà la composition lors de mesure du bore par SIMS, nous avons reproduit indépendamment le décalage observé entre deux laboratoires et ce phénomène s'est révélé stable sur une période de plus d'un an. Cette étude met en lumière le besoin d'ajuster précisément les compositions chimiques des matériaux de référence et des échantillons à analyser. [source]

    Application of High Spatial Resolution Laser Ablation ICP-MS to Crystal-Melt Trace Element Partition Coefficient Determination

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2007
    Maurizio Petrelli
    ICP-MS; ablation laser; éléments en trace; figure de mérite; coefficients de partage entre cristal et liquide In this contribution we evaluate the capabilities of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) using a 12 ,m spot size. Precision, accuracy and detection limits were assessed on the USGS BCR-2G reference material. We demonstrate that the 12 ,m LA-ICP-MS analyses of experimentally-grown amphibole and garnet are in excellent agreement with secondary ion mass spectrometry (SIMS) trace element determinations on the same crystals. The 12 ,m spot size configuration was subsequently used to determine trace element crystal-melt partition coefficients (Dc/m) for a wide range of trace elements in amphibole in equilibrium with a basanitic melt. The following strategy to determine accurately and evaluate Dc/m is proposed. One or more major elements determined previously by electron probe microanalysis (EPMA) was used to ensure consistency between EPMA and the composition of the aerosol produced by the laser ablation. Measured Dc/m values were successively evaluated using the lattice strain model. The use of this strategy significantly improved the precision and accuracy of Dc/m determination when a LA-ICP-MS configuration with a high spatial resolution was employed. Dans cet article nous évaluons les potentialités de l'ablation laser couplée à un spectromètre de masse à plasma induit (LA-ICP-MS) en travaillant avec un diamètre d'impact de 12 ,m. Précision, justesse et limites de détections sont évaluées sur le matériau de référence BCR-2G de l'USGS. Nous démontrons que les analyses LA-ICP-MS faites avec un diamètre de 12 ,m sur les amphiboles et des grenats synthétiques sont en excellent accord avec les déterminations d'éléments en trace effectuées sur les mêmes cristaux par sonde ionique (SIMS). Ce diamètre d'impact de 12 ,m a donc été sélectionné pour déterminer les coefficients de partage cristal/liquide (Dc/m) pour un grand nombre d'éléments en trace dans une amphibole en équilibre avec un liquide basanitique. Nous proposons la stratégie d'analyse suivante, qui assure une détermination exacte des coefficients de partage Dc/m. Un ou plusieurs des éléments majeurs déterminés auparavant par microsonde électronique (EMPA) est utilisé pour garantir la consistance des données entre EMPA et la composition de l'aérosol produit par l'ablation laser. Les Dc/m mesurés sont ensuite évalués en utilisant le modèle de contrainte de réseau. L'utilisation de cette stratégie améliore de manière significative la précision et la justesse des déterminations de Dc/m quand elle est couplée à l'utilisation d'un système LA-ICP-MS de grande résolution spatiale. [source]

    Accurate U-Pb Age and Trace Element Determinations of Zircon by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 3 2004
    Honglin Yuan
    LA-ICP-MS; laser excimer; zircon; géochronologie; éléments en trace Various zircons of Proterozoic to Oligocene ages (1060-31 Ma) were analysed by laser ablation-inductively coupled plasma-mass spectrometry. Calibration was performed using Harvard reference zircon 91500 or Australian National University reference zircon TEMORA 1 as external calibrant. The results agree with those obtained by SIMS within 2s error. Twenty-four trace and rare earth elements (P, Ti, Cr, Y, Nb, fourteen REE, Hf, Ta, Pb, Th and U) were analysed on four fragments of zircon 91500. NIST SRM 610 was used as the reference material and 29Si was used as internal calibrant. Based on determinations of four fragments, this zircon shows significant intra-and inter-fragment variations in the range from 10% to 85% on a scale of 120 ,m, with the variation of REE concentrations up to 38.7%, although the chondrite-normalised REE distributions are very similar. In contrast, the determined age values for zircon 91500 agree with TIMS data and are homogeneous within 8.7 Ma (2s). A two-stage ablation strategy was developed for optimising U-Pb age determinations with satisfactory trace element and REE results. The first cycle of ablation was used to collect data for age determination only, which was followed by continuous ablation on the same spot to determine REE and trace element concentrations. Based on this procedure, it was possible to measure zircon ages as low as 30.37 0.39 Ma (MSWD = 1.4; 2s). Other examples for older zircons are also given. Différents zircons d'âges variant du Protérozoïque à l'Oligocène (1060-31 Ma) ont été analysés par spectrométrie avec source à plasma induit et ablation laser. La calibration a été faite en utilisant le zircon 91500 de référence de Harvard ou le zircon TEMORA 1 de référence de l'Université Nationale Australienne comme calibrant externe. Les résultats sont en accord avec ceux obtenus par SIMS aux erreurs analytiques près (2s). Vingt-quatre éléments en trace et Terres Rares (P, Ti, Cr, Y, Nb, quatorze ETR, Hf, Ta, Pb, Th et U) ont été analysés sur quatre fragments du zircon 91500. Le standard SRM 610 de NIST a été utilisé comme matériau de référence et 29Si comme calibrant interne. À partir des déterminations faites sur ces quatre fragments, ce zircon montre des variations intra et inter fragments de l'ordre de 10%à 85%à une échelle de 120 ,m, avec des variations des concentrations de Terres Rares allant jusquà 38.7%, bien que le spectre de Terres Rares normalisé aux chondrites reste très constant. Au contraire, les âges déterminés pour le zircon 91500 sont en accord avec les résultats de TIMS et sont homogènes à 8.7 Ma près (2s). Une stratégie d'ablation en deux étapes a été développée pour optimiser les déterminations d'âges U-Pb, et avoir des résultats de Terres Rares et d'éléments en trace satisfaisants. Le premier cycle d'ablation était utilisé pour collecter les données nécessaires à la détermination de l'âge seulement et était suivi d'un cycle d'ablation continue sur le même spot, pour déterminer les concentrations en Terres Rares et en éléments en trace. Grâce à cette procédure, il a été possible de mesurer des âges sur zircons aussi récents que 30.37 0.39 Ma (MSWD = 1.4; 2s). D'autres exemples sur des zircons plus vieux sont aussi donnés. [source]

    Influence of liquid bridges on the mechanical behaviour of polydisperse granular materials

    INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 3 2006
    F. Soulié
    Abstract We investigate a polydisperse granular material in which the particle interactions are governed by a capillary force law. The cohesion force for a grain-pair with unequal diameters is expressed as an explicit function of the inter-particle distance and the volume of the liquid bridge. This analytical relation is validated by experiments on a reference material. Then, it is completed by a rupture criterion and cast in the form of a force law that accounts for solid contact, capillary force and rupture characteristics of a grain-pair. Finally, in order to evaluate the influence of capillary cohesion on the macroscopic behaviour, radial and axial compression tests on cylindrical assemblies of wet particles are simulated using a 3D distinct element method. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Limitations of asymmetric parallel-beam geometry

    JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2004
    N. A. Raftery
    Bragg diffraction peak profiles and intensities in asymmetric (,,2,) diffraction using a mirror-based parallel-beam geometry were compared with symmetric parallel-beam (,,2,) and conventional Bragg,Brentano (,,2,) diffraction for a powdered quartz sample and the NIST standard reference material (SRM) 660a (LaB6, lanthanum hexaboride). A comparison of the intensities and line widths (full width at half-maximum, FWHM) of these techniques demonstrated that low incident angles (,,<,5°) are preferable for the parallel-beam setup. For higher , values, if 2,,<,2,, mass absorption reduces the intensities significantly compared with the Bragg,Brentano setup. The diffraction peak shapes for the mirror geometry are more asymmetric and have larger FWHM values than corresponding peaks recorded with a Bragg,Brentano geometry. An asymmetric mirror-based parallel-beam geometry offers some advantages in respect of intensity when compared with symmetric geometries, and hence may be well suited to quantitative studies, such as those involving Rietveld analysis. A trial Rietveld refinement of a 50% quartz,50% corundum mixture was performed and produced adequate results. [source]

    Simultaneous determination of specimen temperature and specimen displacement in high-temperature X-ray diffractometry applying Bragg,Brentano geometry

    JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2002
    M. Beck
    Temperature uncertainty and unknown specimen displacement are the most severe errors in high-temperature X-ray diffractometry, in particular when using a strip heater mounted on a Bragg,Brentano goniometer. A method is presented that enables the simultaneous determination of the specimen displacement and the temperature of the sample. The method splits the determination of the aberrations into two steps: at room temperature and at elevated temperature. It is based on the use of a reference material as an internal standard. An experimental example applying the method to a specific material is given, and shows that the method provides correct data. [source]