The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Eleni Milioni - One of the best experts on this subject based on the ideXlab platform.
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comparing-thermal-resistivity-between-semi-crystalline-and-amorphous-polymers.pdf
internal, 2020Co-Authors: Eleni MilioniAbstract:guarded hot plates, including recent developments and sources of reference materials”, Meas. Sci. technol., 12, 2001, pp. R89–R98. 2. C. T’Joen, Y. Park and Q
Wolfgang Pritzkow - One of the best experts on this subject based on the ideXlab platform.
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The need for new isotope Reference Materials
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Jochen Vogl, Martin Rosner, Wolfgang PritzkowAbstract:Isotope Reference Materials are needed to calibrate and validate analytical procedures used for the determination of isotope amount ratios, procedurally defined isotope ratios or so-called δ values. In contrast to the huge analytical progress in isotope ratio analytics, the production of isotope Reference Materials has not kept pace with the increasing needs of isotope analysts. Three representative isotope systems are used to explain the technical and non-technical difficulties and drawbacks, on one hand, and to demonstrate what can be achieved at its best, on the other hand. A clear statement is given that new isotope Reference Materials are needed to obtain traceable and thus comparable data, which is essential for all kinds of isotope research. The range of available isotope Reference Materials and δ Reference Materials should be increased and matrix Reference Materials certified for isotope compositions or δ values, which do not exist yet, should be provided.
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Isotope Reference Materials for present and future isotope research
Journal of Analytical Atomic Spectrometry, 2010Co-Authors: Jochen Vogl, Wolfgang PritzkowAbstract:Isotope Reference Materials are essential to enable reliable and comparable isotope data. This article reviews the work in this field within the past years. The focus is on all stable elements, except for classical stable isotopes (H, C, N, O, S) and for radioactive elements. Currently available isotope Reference Materials are listed. The limitations of synthetic isotope mixtures being used to characterize these Materials are discussed, as well as the limitations of the isotope Reference Materials, such as uncertainty and homogeneity. The needs for present research on isotope variations are being considered and are compared to the limitations of current isotope Reference Materials. This disagreement between both can only be solved by providing isotope Reference Materials defining a δ-scale for each element of interest. Such Materials should be provided with additional data on isotope abundances whenever possible. As an outlook a possible outline for a new program on isotope Reference Materials is discussed.
Jochen Vogl - One of the best experts on this subject based on the ideXlab platform.
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assessment of international Reference Materials for isotope ratio analysis iupac technical report
Pure and Applied Chemistry, 2014Co-Authors: Willi A Brand, Jochen Vogl, Martin Rosner, Tyler B Coplen, Thomas ProhaskaAbstract:Since the early 1950s, the number of international measurement standards for anchoring stable isotope delta scales has mushroomed from 3 to more than 30, expanding to more than 25 chemical elements. With the development of new instrumentation, along with new and improved measurement procedures for studying naturally occurring isotopic abundance variations in natural and technical samples, the number of internationally distributed, secondary isotopic Reference Materials with a specified delta value has blossomed in the last six decades to more than 150 Materials. More than half of these isotopic Reference Materials were produced for isotope-delta measurements of seven elements: H, Li, B, C, N, O, and S. The number of isotopic Reference Materials for other, heavier elements has grown considerably over the last decade. Nevertheless, even primary international measurement standards for isotope-delta measurements are still needed for some elements, including Mg, Fe, Te, Sb, Mo, and Ge. It is recommended that authors publish the delta values of internationally distributed, secondary isotopic Reference Materials that were used for anchoring their meas - urement results to the respective primary stable isotope scale.
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The need for new isotope Reference Materials
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Jochen Vogl, Martin Rosner, Wolfgang PritzkowAbstract:Isotope Reference Materials are needed to calibrate and validate analytical procedures used for the determination of isotope amount ratios, procedurally defined isotope ratios or so-called δ values. In contrast to the huge analytical progress in isotope ratio analytics, the production of isotope Reference Materials has not kept pace with the increasing needs of isotope analysts. Three representative isotope systems are used to explain the technical and non-technical difficulties and drawbacks, on one hand, and to demonstrate what can be achieved at its best, on the other hand. A clear statement is given that new isotope Reference Materials are needed to obtain traceable and thus comparable data, which is essential for all kinds of isotope research. The range of available isotope Reference Materials and δ Reference Materials should be increased and matrix Reference Materials certified for isotope compositions or δ values, which do not exist yet, should be provided.
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Isotope Reference Materials for present and future isotope research
Journal of Analytical Atomic Spectrometry, 2010Co-Authors: Jochen Vogl, Wolfgang PritzkowAbstract:Isotope Reference Materials are essential to enable reliable and comparable isotope data. This article reviews the work in this field within the past years. The focus is on all stable elements, except for classical stable isotopes (H, C, N, O, S) and for radioactive elements. Currently available isotope Reference Materials are listed. The limitations of synthetic isotope mixtures being used to characterize these Materials are discussed, as well as the limitations of the isotope Reference Materials, such as uncertainty and homogeneity. The needs for present research on isotope variations are being considered and are compared to the limitations of current isotope Reference Materials. This disagreement between both can only be solved by providing isotope Reference Materials defining a δ-scale for each element of interest. Such Materials should be provided with additional data on isotope abundances whenever possible. As an outlook a possible outline for a new program on isotope Reference Materials is discussed.
Fangzhen Teng - One of the best experts on this subject based on the ideXlab platform.
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potassium isotopic compositions of international geological Reference Materials
Chemical Geology, 2019Co-Authors: Xinyang Chen, Tianyi Huang, Ronald S Sletten, Dan Zhu, Fangzhen TengAbstract:Abstract There is a renewed interest in K isotope geochemistry driven by the advances in analytical precision and it is emerging as a useful tracer in a variety of disciplines ranging from Earth sciences to biology. However, high-quality K isotopic data for Reference Materials are still limited but highly needed. Here, we report high-precision stable K isotopic compositions (δ41K) for 23 commercially available international Reference Materials, including igneous, sedimentary, and metamorphic rocks, as well as an in-house seawater standard. Potassium in digested samples was separated by cation-exchange chromatography with Bio-Rad AG50W-X8 (200–400 mesh) resin in 0.5 N HNO3 media. Potassium isotopes were measured on a Nu Plasma II high-resolution MC-ICPMS. The reproducibility of K isotopic analysis, based on over one year of measurements of pure K solutions and rock standards, was ≤0.06‰ (95% confidence interval). Synthetic solutions made by mixing single element standards to represent various rock matrices confirmed the accuracy of our methods. The 23 Reference Materials have δ41K values ranging from −0.562‰ to −0.253‰ and the seawater standard has a much higher δ41K value of 0.143‰. The comprehensive dataset presented here provides a Reference for quality control and inter-laboratory comparison of high-precision K isotopic analyses for future studies.
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magnesium isotopic compositions of international geological Reference Materials
Geostandards and Geoanalytical Research, 2015Co-Authors: Fangzhen Teng, Wei Yang, Shengao Liu, Fatemeh Sedaghatpour, Shuijiong Wang, Kangjun Huang, Mingxing Ling, Yan Xiao, Xiaoming LiuAbstract:Magnesium isotopic compositions are reported for twenty-four international geological Reference Materials including igneous, metamorphic and sedimentary rocks, as well as phlogopite and serpentine minerals. The long-term reproducibility of Mg isotopic determination, based on 4-year analyses of olivine and seawater samples, was ≤ 0.07‰ (2s) for δ26Mg and ≤ 0.05‰ (2s) for δ25Mg. Accuracy was tested by analysis of synthetic Reference Materials down to the quoted long-term reproducibility. This comprehensive dataset, plus seawater data produced in the same laboratory, serves as a Reference for quality assurance and inter-laboratory comparison of high-precision Mg isotopic data. Les compositions isotopiques du magnesium sont fournies pour vingt-quatre materiaux geologiques de Reference internationaux, comprenant des roches ignees, metamorphiques et sedimentaires, ainsi qu'une phlogopite et des serpentines. La reproductibilite a long terme de la determination isotopique du Mg, basee des analyses sur quatre ans d’echantillons d'olivine et d'eau de mer, etait ≤ 0.07% (2s) pour δ26Mg et ≤ 0.05% (2s) pour δ25Mg. La precision a ete testee par l'analyse de materiaux de Reference synthetiques jusqu’a la reproductibilite a long terme indiquee. Cette base de donnees complete, ainsi que des donnees d'eau de mer produites dans le meme laboratoire, servent de Reference pour l'assurance qualite et la comparaison inter-laboratoires de haute precision des donnees isotopiques du Mg.
Klaus Peter Jochum - One of the best experts on this subject based on the ideXlab platform.
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Reference Materials in geochemical and environmental research
Treatise on Geochemistry, 2014Co-Authors: Klaus Peter Jochum, Jacinta EnzweilerAbstract:In all fields of geochemistry, cosmochemistry, and environmental research, Reference Materials play an important role. They are used as samples for calibration of analytical instruments and to establish metrological traceability to measurements, quality control and assurance, and interlaboratory comparisons. The International Organization for Standardization Committee on Reference Materials (ISO/REMCO) works to establish and update internationally agreed guidelines concerning terminology, production, characterization, certification, and use of Reference Materials. Many Reference Materials are homogeneous rock powders, synthetic and natural silicate glasses, minerals, and environmental Materials. So-called delta zero, radioactive and radiogenic isotopic Reference Materials are necessary for normalization purposes of isotope ratio measurements. Geochemists can easily have access to information about Reference Materials using the GeoReM database. Although many rock Reference Materials have been produced, only few of them have been certified by ISO-compatible procedures. There is a need for microanalytical Reference Materials, especially for homogeneous and well-characterized mineral samples. The situation is also unsatisfactory for isotopic Reference Materials. Many isotopic Reference Materials are heterogeneous in the isotopic composition, because they were made from oxides or metal, do not have certified values, and have isotope ratios much far from any natural sample or not available any more.
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Geochemical and Environmental Reference Materials and the GeoReM Database
Rock and Mineral Analysis, 2009Co-Authors: Klaus Peter Jochum, X.-h. WangAbstract:In all fields of geochemical and environmental sample analysis, Reference Materials play an increasingly important role. Although the provider of an analytical result must document the measurement process used to establish traceability links, most publications do not contain data of Reference Materials. Therefore, the focus of this paper is to clarify the role and use of Reference Materials and certified Reference Materials, to discuss the importance of Reference Materials for geoanalytical work and to present the GeoReM database for Reference Materials of geological and environmental interests. The GeoReM database contains published analytical data, compiled data and metadata for 1880 geochemical and environmental Reference Materials including 156 Chinese Reference Materials, provides geoanalysts with details of those samples of particular relevance to applications. Preferred values and their uncertainties are also provided in this database. Although most of the GeoReM preferred values are not ISO compliant, they have a high level of confidence and are therefore useful for calibration purposes and quality control. The importance of future input of Chinese Reference Materials published in Chinese scientific journals is pointed out.
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Reference Materials in geochemistry and environmental research and the GeoReM database
Chemical Geology, 2008Co-Authors: Klaus Peter Jochum, Uwe NohlAbstract:Abstract In all fields of geochemical and environmental sample analysis, Reference Materials play an increasingly important role. Although the provider of an analytical result must document the measurement process used to establish traceability links, most publications do not contain data of Reference Materials. Therefore, the focus of this paper is to clarify the role and use of Reference Materials and certified Reference Materials, to discuss the importance of Reference Materials for geoanalytical work and to present the GeoReM database for Reference Materials of geological and environmental interest. The GeoReM database contains published analytical data, compiled data and metadata for about 1800 geochemical and environmental Reference Materials, provides geoanalysts with details of those samples of particular relevance to applications. Preferred values and their uncertainties are also provided in this database. Although most of the GeoReM preferred values are not ISO compliant, they have a high level of confidence and are therefore useful for calibration purposes and quality control.
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Reference Materials in Geoanalytical and Environmental Research ‐ Review for 2006 and 2007
Geostandards and Geoanalytical Research, 2008Co-Authors: Klaus Peter Jochum, Stefanie M. BruecknerAbstract:This review surveys the literature on Reference Materials for geological and environmental research for the two year period 2006–2007. In this time ca. 1200 publications appeared containing analytical data on Reference Materials, indicating that their importance for analytical work has been recognised by geochemists and environmental scientists. Although many Reference Materials exist, there remains a pressing need for further samples, especially for certified rock Reference Materials, homogeneous Reference glasses, mineral Reference Materials and so-called delta-zero Materials for normalisation purposes of stable isotopes. This review focuses on six topics: rock Reference Materials, Reference Materials for platinum-group elements, Reference glasses, mineral Reference Materials, environmental Reference Materials (seawater, soil) and isotopic Reference Materials (radiogenic, stable isotopes). In addition, a short description is given of the GeoReM database for Reference Materials of geological and environmental interest, which contains analytical data from the publications discussed in this review.
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Reference Materials in Geoanalytical Research -Review for 2004 and 2005
Geostandards and Geoanalytical Research, 2006Co-Authors: Klaus Peter Jochum, Matthias WillboldAbstract: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.
