TY - JOUR A1 - Kipphardt, Heinrich A1 - De Bièvre, P. A1 - Taylor, P.D.P. T1 - New mathematical models with associated equations for isotope dilution mass spectrometry (IDMS) N2 - Vector models which progressively lead to a general model for isotope dilution mass spectrometry (IDMS) are presented for the case of two lsquomonitor isotopesrsquo and one blend involved. They enable one to find the boundary conditions for performing IDMS, and cover the cases of highly enriched isotopes, radioactive isotopes and ratios that are given with different denominator. The models identify the key measurements in their simplest form as well as the conditions which minimise the measurement effort and in some cases the propagated measurement uncertainties. The equations are discussed and compared with other published IDMS equations. Combined with discussion on fundamental aspects of IDMS, this results in an even more lsquogeneralrsquo but also more complex IDMS equation. KW - Isotope dilution mass spectrometry KW - IDMS KW - Measurement equation PY - 2004 DO - https://doi.org/10.1007/s00216-003-2232-3 SN - 1618-2642 SN - 1618-2650 VL - 378 IS - 2 SP - 330 EP - 341 PB - Springer CY - Berlin AN - OPUS4-3062 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diemer, J. A1 - Vogl, Jochen A1 - Quétel, C.R. A1 - Linsinger, T. A1 - Taylor, P.D.P. A1 - Lamberty, A. A1 - Pauwels, J. T1 - SI-traceable certification of the amount content of cadmium below the ng g-1 level in blood samples by isotope dilution ICP-MS applied as a primary method of measurement N2 - The development and implementation of a method for the certification of cadmium in blood samples at low ng g-1 and sub ng g-1 levels is described. The analytical procedure is based on inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) applied as a primary method of measurement. Two different sample digestion methods, an optimized microwave digestion procedure using HNO3 and H2O2 as oxidizing agents and a high-pressure asher digestion procedure, were developed and compared. The very high salt content of the digests and the high molybdenum content, which can cause oxide-based interferences with the Cd isotopes, were reduced by a chromatographic matrix separation step using an anion-exchange resin. All isotope ratio measurements were performed by a quadrupole ICP-MS equipped with an ultrasonic nebulizer with membrane desolvator. This sample introduction set-up was used to increase sensitivity and minimize the formation of oxides (less MoO+ interference with the Cd isotopes). Because of the very low Cd concentrations in the samples and the resulting need to minimize the procedural blank as much as possible, all sample-processing steps were performed in a clean room environment. Detection limits of 0.005 ng g-1 Cd were achieved using sample weights of 2.7 g. The method described was used to re-certify the cadmium content of three different blood reference materials from the Community Bureau of Reference (BCR) of the European Commission (BCR-194, BCR-195, BCR-196). Cadmium concentrations ranged between ~0.2 ng g-1 and ~12 ng g-1. For these materials, SI-traceable certified values including total uncertainty budgets according to ISO and Eurachem guidelines were established. PY - 2001 DO - https://doi.org/10.1007/s002160100813 SN - 0937-0633 VL - 370 SP - 492 EP - 498 PB - Springer CY - Berlin AN - OPUS4-3363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hearn, R. A1 - Berglund, M. A1 - Ostermann, Markus A1 - Pusticek, N. A1 - Taylor, P.D.P. T1 - A comparison of high accuracy isotope dilution techniques for the measurement of low level sulfur in gas oils N2 - A comparison of high accuracy methods for the analysis of total sulfur in gas oils by three metrology institutes is described. The work contains a comparison of three different aspects of the analysis: sample digestion, instrumental measurement and isotope dilution strategies. Thermal ionisation mass spectrometry (TIMS) in combination with high pressure asher (HPA) or Carius tube digestion has traditionally been used for such high accuracy analysis. However, this paper demonstrates that the faster, less laborious technique of ICP-MS in combination with microwave digestion is equally capable. Results from the comparison experiments show excellent agreement for fuel samples containing sulfur concentrations in the range 11–200 µg g-1. This excellent agreement across the different sample preparation, measurement and isotope dilution techniques has been exploited in the certification of two new diesel fuel reference materials. KW - Sulfur KW - Gas oil KW - Isotope dilution KW - ICP-MS KW - TIMS KW - Uncertainty PY - 2005 DO - https://doi.org/10.1016/j.aca.2004.10.070 SN - 0003-2670 SN - 1873-4324 SN - 0378-4304 VL - 532 IS - 1 SP - 55 EP - 60 PB - Elsevier CY - Amsterdam AN - OPUS4-7280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogl, Jochen A1 - Quétel, C. A1 - Ostermann, Markus A1 - Papadakis, I. A1 - Van Nevel, L. A1 - Taylor, P.D.P. T1 - Contribution to the certification of B, Cd, Mg, Pb, Rb, Sr, and U in a natural water sample for the International Measurement Evaluation Programme Round 9 (IMEP-9) using ID-ICP-MS N2 - The present paper describes the contribution of the Institute for Reference Materials and Measurements to the certification of B, Cd, Mg, Pb, Rb, Sr, and U amount contents in a natural water sample, in round 9 of the International Measurement Evaluation Programme (IMEP-9). The analytical procedure to establish the reference values for B, Cd, Mg, Pb, Rb, Sr, and U amount contents was based on isotope dilution inductively coupled plasma-mass spectrometry used as a primary method of measurement. Applying this procedure reference values, traceable to the SI, were obtained for the natural water sample of IMEP-9. For each of the certified amount contents presented here a total uncertainty budget was calculated using the method of propagation of uncertainties according to ISO and EURACHEM guidelines. The measurement procedures, as well as the uncertainty calculations are described for all seven elements mentioned above. In order to keep the whole certification process transparent and so traceable, the preparations of various reagents and materials as well as the sample treatment and blending, the measurements themselves, and finally the data treatment are described in detail. Explanations focus on Pb as a representative example. The total uncertainties (relative) obtained were less than 2% for all investigated elements at amount contents in the pmol/kg up to the high 7mol/kg range, corresponding to low 7g/kg and mg/kg levels. KW - IMEP-9 KW - ID-ICP-MS KW - IDMS KW - Uncertainty budget KW - Certification PY - 2000 DO - https://doi.org/10.1007/s007690000145 SN - 0949-1775 SN - 1432-0517 VL - 5 SP - 272 EP - 279 PB - Springer CY - Berlin AN - OPUS4-7216 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nelms, S. A1 - Quétel, C. A1 - Prohaska, T. A1 - Vogl, Jochen A1 - Taylor, P.D.P. T1 - Evaluation of detector dead time calculation models for ICP-MS KW - ICP-MS KW - Dead time KW - Uncertainty PY - 2001 DO - https://doi.org/10.1039/b007913h SN - 0267-9477 SN - 1364-5544 VL - 16 IS - 4 SP - 333 EP - 338 PB - Royal Society of Chemistry CY - London AN - OPUS4-7219 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 DO - 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 DO - 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 - TY - JOUR A1 - Kipphardt, Heinrich A1 - Russe, K. A1 - Bréas, O. A1 - Taylor, P.D.P. T1 - Conversion of Carbon into CF4 for SI-Traceable Measurements of Absolute Carbon Isotope Amount Ratios: A Feasibility Study N2 - The feasibility of performing SI-traceable carbon isotope amount ratio measurements following conversion of carbon into CF4 was studied. A procedure for the direct fluorination of carbon with elemental fluorine was developed, and the conversion step was checked for losses, blank contributions, and the absence of systematic isotope effects. Gas chromatography was used to identify and quantify the gaseous fluorination products and to isolate CF4 from byproducts. After fluorination of graphite carbon, CF4 and perfluoroalkanes with up to six carbon atoms were observed as reaction products. Within an uncertainty of 10%, the graphite carbon was fully recovered in the gaseous carbon fluorides, with the main product being CF4 (80-90%) and C2F6 as the major byproduct. The fluorination and GC procedures were found to introduce an alteration not bigger than 0.03 ± 0.04” on the isotopic composition of CF4. Carbon blank contributions introduced during the fluorination procedure were below 0.5% relative to a typical sample of 4 mg of carbon. For two of the materials investigated, the carbon isotope ratios measured on a differential mass spectrometer were reproducible within a standard deviation of ~0.1” for several individual fluorinations. For these materials, the developed fluorination procedure is a straightforward process, which can be used as a foundation to establish SI-traceable measurements of carbon isotope amount ratios. However, for the third graphite material the formation of byproducts (C2F6-C6F14) was found to induce significant isotopic fractionation. PY - 2002 DO - https://doi.org/10.1021/ac015700g SN - 0003-2700 SN - 1520-6882 VL - 74 SP - 3199 EP - 3205 PB - American Chemical Society CY - Washington, DC AN - OPUS4-1408 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 DO - 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 -