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A highly accurate gas chromatographic analytical method has been developed for the determination of the composition of gas
mixtures. It was tested using a reference gas as an example consisting of 3.5% of CO, 14% of CO2, 0.2% of propane and residual N2 intended for the use in vehicle emission measurements. The method is based on comparison measurements with samples of a calibration
gas, whose composition is iteratively adapted to that of the sample investigated using a gravimetric gas mixing method. For
the gas chromatographic measurement, a molecular sieve column and a polymer column are used in parallel and in isothermal
operation. All gas components can be determined by a single gas chromatographic measurement, and the relative uncertainty
of measurement achievable is ?0.4%.
Received: 6 March 1996/Revised: 30 May 1996/Accepted: 6 June 1996 相似文献
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Axel Pramann Olaf Rienitz Detlef Schiel Bernd Güttler 《International journal of mass spectrometry》2011,299(2-3):78-86
The isotopic abundances and thus molar mass M(Si) of a silicon crystal material with natural isotopic abundances have been measured for the first time using multicollector-ICP-mass spectrometry (MC-ICP-MS) in combination with a novel concept of a modified isotope dilution mass spectrometry (IDMS)-method. This experimental work is the further development of part 1 of this series of papers. While part 1 describes the theoretical background and the mathematical derivation of the novel concept in detail, the measurements presented here serve to validate the novel concept and give experimental proof of its capability. Moreover, the also new method for the analytical calculation of calibration factors needed in the determination of absolute isotope amount ratios has been tested successfully. Silicon isotopic abundances have been measured directly from an aqueous alkaline matrix following a new sample preparation protocol developed within the framework of this study. A molar mass of M(Si) = 28.08548(13) g/mol with an associated relative uncertainty of urel = 4.6 × 10?6 (k = 1) has been measured. This is in excellent agreement with the current IUPAC value for the molar mass of natural silicon M(Sinat) = 28.08550(15) g/mol with urel = 5.3 × 10?6 (k = 1). An uncertainty budget according to the Guide to the Expression of Uncertainty in Measurement (GUM) was calculated to assess the presented results and to validate the novel concept with the help of experimental data. The development of a new experimental procedure is presented in detail and the contributions to the uncertainty are discussed in comparison to part 1 of this work. 相似文献
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The combined use of silica-based chromatographic supports with immobilized affinity ligands can be used in many preparative and analytical applications. One example is the use of silica-based affinity columns in HPLC, giving rise to a method known as high-performance affinity chromatography (HPAC). This review discusses the role that silica has played in the development of affinity chromatography and HPAC and the applications of silica in these methods. This includes a discussion of the types of ligands that have been employed with silica and the methods by which these ligands have been immobilized. Various formats have also been presented for the use of silica in affinity chromatographic methods, including assays involving direct or indirect analyte detection, on-line or off-line affinity extraction, and chiral separations. The use of silica-based affinity columns in studies of biological systems based on zonal elution and frontal analysis methods will also be considered. 相似文献
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Olaf Rienitz Detlef Schiel Bernd Güttler Michael Koch Ulrich Borchers 《Accreditation and quality assurance》2007,12(12):615-622
Metrologically traceable reference values add an essential benefit to interlaboratory comparisons: unlike consensus values,
they can be used to establish national and international comparability. Furthermore, the participating laboratories obtain
a reliable and unbiased benchmark to check their results for accuracy. Usually, metrologically traceable reference values
are obtained by so-called primary methods which demand excessive efforts at great expense. Within the framework of two national drinking-water interlaboratory comparisons
(proficiency testing rounds), a new approach to provide metrologically traceable reference values was applied. It is solely
based on existing data which were collected during the comparison itself. Lead (Pb) measurements serve as an example to show
how metrologically traceable reference values were derived from the lead amount added during sample preparation and the amount
of lead already present in the drinking-water matrix used to prepare these samples. Within this approach, the matrix content
is calculated in a way similar to a standard addition experiment. An uncertainty budget for the reference value was set up
which describes the link to the corresponding SI units. Isotope dilution mass spectrometry (IDMS) as a primary method was
used to validate this approach in the case of cadmium, chromium, copper, lead, and nickel. 相似文献
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Olaf Rienitz Axel Pramann Detlef Schiel 《International journal of mass spectrometry》2010,289(1):47-53
The development of a new method for the experimental determination of absolute isotopic abundances using a modified isotope dilution mass spectrometry (IDMS) technique is described. The intention and thus main application will be the quantification of molar masses M of highly enriched materials with improved measurement uncertainty (Urel(M) ≈ 10?8 with k = 2). In part 1 of the current work, the theoretical foundation of the new method and its mathematical derivation is shown in detail, while part 2 will cover the experiments based on the new method described. Its core idea is the introduction of a virtual element (VE) consisting of all isotopes but the one having the largest or smallest abundance. IDMS is used to determine the mass fraction of this VE in its matrix, namely the element itself. A new set of equations serve to calculate all isotopic abundances (even the large one omitted with the introduction of the VE) merely from the mass fraction of the VE. A comprehensive uncertainty budget according to the Guide to the Expression of Uncertainty in Measurement (GUM) was set up in order to discuss and validate the novel concept. The hypothetical input data of the uncertainty budget were estimated to resemble a silicon material highly enriched with respect to 28Si used in the context of the international Avogadro Project. Considering the calculated results, the experimental determination of the molar mass of the above mentioned silicon seems very promising. As far as the authors know, this will be the first time IDMS was applied to determine a molar mass. 相似文献
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Liandi Ma Liuxing Feng A. Hioki K. H. Cho J. Vogl A. Berger G. Turk S. Macleod G. Labarraque W. F. Tong D. Schiel C. Yafa L. Valiente L. A. Konopelko C. Quetel P. Vermaercke J. V. L. Manzano M. Linsky E. Cortés S. Tangpitayakul L. Plangsangmas L. Bergamaschi R. Hearn 《Accreditation and quality assurance》2010,15(1):39-44
The CCQM-P106 pilot study was organized by the inorganic working group of the Comité Consultatif pour la Quantité de Matière (CCQM) as a feasibility comparison to study the applicability of different analysis methods to the polypropylene sample and test the abilities of the participants for measuring the Cd, Cr, Hg and Pb in polypropylene. National Institute of Metrology P.R. China (NIM) acted as the coordinating laboratory of this pilot study. There were 21 laboratories that submitted the final results. The median values of the mass fraction of Cd, Cr, Hg and Pb were 36.12 mg kg?1 (the median absolute deviation about the median (MADe) = 0.46 mg kg?1), 252.5 mg kg?1 (MADe = 3.4 mg kg?1), 387.0 mg kg?1 (MADe = 10.1 mg kg?1) and 466.2 mg kg?1 (MADe = 8.9 mg kg?1), respectively. Isotope dilution mass spectrometry (IDMS), inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES), atomic absorption spectrometry (AAS), instrumental neutron activation analysis (INAA) and X-ray fluorescence (XRF) measurement methods were used, and microwave digestion was used by the most of the participants. In general, very good agreement of the results was observed. Moreover, compared to the results of other methods, the results of IDMS still showed less spread amongst laboratories and had a smaller uncertainty. In addition, the results of some analytes used by XRF and INAA also got satisfactory agreement with the median value. 相似文献
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