TY - JOUR A1 - Kipphardt, Heinrich A1 - Valkiers, S. A1 - Taylor, P.D.P. A1 - De Bièvre, P. T1 - Calibration in isotopic measurements N2 - The meaning of calibration in general and in the field of isotopic measurements in particular is described, stressing the fundamental difference between calibration as an aim and tools to achieve calibration. The role of proper uncertainty budgeting as a prerequisite for establishing a “calibrated” measurement is explained. It leads to the recommendation that the quality of the uncertainty statement should be heavily weighed when ranking or judging “calibrated” isotopic measurement results evaluated by the Commission on Atomic Weight and Isotopic Abundances. KW - Calibration KW - Uncertainty KW - Measurement result KW - Isotopic measurement PY - 2000 U6 - https://doi.org/10.1016/S1387-3806(00)00162-7 SN - 0168-1176 SN - 0020-7381 SN - 1387-3806 SN - 1873-2798 VL - 198 IS - 1-2 SP - 71 EP - 76 PB - Elsevier CY - Amsterdam AN - OPUS4-912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kipphardt, Heinrich A1 - Ding, T. A1 - Valkiers, S. A1 - Quetel, C. A1 - De Bièvre, P. A1 - Taylor, P. A1 - Gonfiantini, R. T1 - Preparation of two synthetic isotope mixtures for the calibration of isotope amount ratio measurements of sulfur N2 - Two synthetic isotope mixtures for the calibration of sulfur isotope amount ratio measurements were gravimetrically prepared from high purity Ag2S materials enriched in 32S, 33S, and 34S. The mixtures were made so as to closely resemble the (natural) isotopic composition of the materials to be “calibrated”. This allowed a totally independent evaluation, on the same samples, of the relative combined uncertainty of: (a) the procedure to perform direct measurements of the amount of substance ratios of gas isotopes in the redetermination of the Avogadro constant and (b) the gravimetric preparation procedure. The result of both procedures, mass spectrometry and gravimetry, agree to a relative uncertainty of 3 × 10-4 for sulfur amount ratio measurements of the major abundant isotopes. Thus it seems that a direct measurement of isotopic gas mixtures (e.g. of natural isotopic composition) is now possible for sulfur—and probably also for other gaseous isotopes—without necessarily having to rely on “calibration” by means of values provided by measurements of gravimetrically prepared isotope mixtures. However, synthetic mixtures may be needed for validation and verification purposes, in particular for quality assurance. KW - Sulfur KW - Absolute isotope amount ratio KW - Synthetic isotope mixtures KW - Sulfur hexafluoride KW - Mass spectrometry PY - 2000 U6 - https://doi.org/10.1016/S1387-3806(99)00235-3 SN - 0168-1176 SN - 0020-7381 SN - 1387-3806 SN - 1873-2798 VL - 197 IS - 1-3 SP - 131 EP - 137 PB - Elsevier CY - Amsterdam AN - OPUS4-913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kipphardt, Heinrich A1 - Ruße, K. A1 - Bréas, O. A1 - Valkiers, S. A1 - Taylor, P. T1 - Fluorination of organic materials into CF4 for the measurements of carbon isotope ratios T2 - V Isotope Workshop CY - Krakow, Poland DA - 2000-07-01 PY - 2000 IS - poster P1-1 AN - OPUS4-914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kipphardt, Heinrich A1 - Valkiers, S. A1 - Aregbe, Y. A1 - Bréas, O. A1 - Taylor, P. A1 - Ding, T. ED - Gills, T. T1 - Gravimetrically Prepared Isotope Mixtures to Produce Isotopic Reference Materials for Sulfur with SI Traceable Ratios T2 - 8th International Symposium on Biological and Environmental Reference Materials ; 8th BERM CY - Bethesda, MD, USA DA - 2000-09-17 PY - 2001 SN - 1618-2642 VL - 370 IS - 2-3 SP - 141 PB - Springer CY - Berlin AN - OPUS4-990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kipphardt, Heinrich A1 - Aregbe, Y. A1 - Valkiers, S. A1 - Norgaard, J. A1 - De Bièvre, P. A1 - Taylor, P.D.P. A1 - Poths, J. T1 - A primary isotopic gas standard for krypton with values for isotopic composition and molar mass traceable to the Système International d'Unités N2 - Isotope amount ratios of krypton were measured on subsamples from one large batch of high purity krypton separated from the atmosphere. Synthetic mixtures of enriched krypton isotopes were used to “calibrate” the measurements with small uncertainties. The result is a primary isotopic gas standard (PIGS) IRMM-2030 with certified values for isotope ratios, isotopic composition, and molar mass of krypton with small combined uncertainties uc, evaluated according to the ISO/BIPM Guide (GUM). It is commercially available from IRMM-Geel or from MESSER (Duisburg, D). The certified krypton isotope amount ratios in the PIGS IRMM-2030 are as follows: n(78Kr)/n(84Kr)=0.006 232 5(55), n(80Kr)/n(84Kr)=0.040 107(17), n(82Kr)/n(84Kr)=0.203 43(12), n(83Kr)/n(84Kr)=0.201 79(11), and n(86Kr)/n(84Kr)=0.303 205(59) with expanded uncertainty U=kuc and coverage factor k=2. The molar mass of Kr in this sample is M(Kr)=83.798 02(16) g/mol. These values are in good agreement with published measurements of atmospheric krypton but have smaller combined uncertainties and are “calibrated” by means of synthetic isotope mixtures. The values of the PIGS are traceable to the SI. Measurements of isotope amount ratios of krypton in other samples can be linked to SI using this PIGS. KW - Molar mass KW - Isotopic composition KW - Primary isotopic gas standard KW - Gas isotope mass spectrometry KW - Isotope amount ratio KW - Traceability KW - SI KW - Krypton PY - 2001 U6 - https://doi.org/10.1016/S1387-3806(00)00397-3 SN - 0168-1176 SN - 0020-7381 SN - 1387-3806 SN - 1873-2798 VL - 206 SP - 129 EP - 136 PB - Elsevier CY - Amsterdam AN - OPUS4-1087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kipphardt, Heinrich A1 - Ding, T. A1 - Valkiers, S. A1 - De Bièvre, P. A1 - Taylor, P.D.P. A1 - Gonfiantini, R. A1 - Krouse, R. T1 - Calibrated sulfur isotope abundance ratios of three IAEA sulfur isotope reference materials and V-CDT with a reassessment of the atomic weight of sulfur N2 - Calibrated values have been obtained for sulfur isotope abundance ratios of sulfur isotope reference materials distributed by the IAEA (Vienna). For the calibration of the measurements, a set of synthetic isotope mixtures were prepared gravimetrically from high purity Ag2S materials enriched in32S, 33S, and 34S. All materials were converted into SF6 gas and subsequently, their sulfur isotope ratios were measured on the SF5+ species using a special gas source mass spectrometer equipped with a molecular flow inlet system (IRMM’s Avogadro II amount comparator). Values for the 32S/34S abundance ratios are 22.650 4(20), 22.142 4(20), and 23.393 3(17) for IAEA-S-1, IAEA-S-2, and IAEA-S-3, respectively. The calculated 32S/34S abundance ratio for V-CDT is 22.643 6(20), which is very close to the calibrated ratio obtained by Ding et al. (1999). In this way, the zero point of the VCDT scale is anchored firmly to the international system of units SI. The 32S/33S abundance ratios are 126.942(47), 125.473(55), 129.072(32), and 126.948(47) for IAEA-S-1, IAEA-S-2, IAEA-S-3, and V-CDT, respectively. In this way, the linearity of the V-CDT scale is improved over this range. The values of the sulfur molar mass for IAEA-S-1 and V-CDT were calculated to be 32.063 877(56) and 32.063 911(56), respectively, the values with the smallest combined uncertainty ever reported for the sulfur molar masses (atomic weights). PY - 2001 U6 - https://doi.org/10.1016/S0016-7037(01)00611-1 SN - 0016-7037 SN - 1872-9533 VL - 65 IS - 15 SP - 2433 EP - 2437 PB - Elsevier Science CY - New York, NY AN - OPUS4-1137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -