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 - Russe, K. A1 - Broekaert, J.A.C. T1 - Determination of main and minor components of silicon based materials by a combustion with elemental fluorine. Separation of gaseous fluorination products by carrier gas distillation and gas mass spectrometry N2 - For the determination of main and minor components in silicon-based ceramic powders, a decomposition by a combustion with elemental fluorine and separation of the volatile fluorination products by a carrier-gas distillation with a subsequent detection by quadrupole mass spectrometry is described. The necessity and success of the separation step is demonstrated for the determination of boron as a minor constituent in SiC, where the spectral interferences of silicon on the boron signals are decreased considerably. The method developed is shown to be directly applicable to determination of silicon in Si3N4, SiC, and SiO2. The determination of nitrogen in Si3N4 requires additional effort, to separate nitrogen from the excess of fluorine. For the determination of boron, a complete mobilization of BF3 is assured by the presence of an adequate amount of GeF4. Analysis results obtained with different types of calibration show a precision of 30 g for boron at the milligram-per-gram level and a precision between 0.5 and 2% (m/m) for the main components, silicon and nitrogen. Within these standard deviations, the results agree well with the values expected from the stoichiometry, with the results for silicon and boron obtained by wet chemical decomposition and slurry techniques in combination with ICP-OES and with the results for nitrogen obtained by carrier gas heat extraction. PY - 2000 DO - https://doi.org/10.1021/ac991238c SN - 0003-2700 SN - 1520-6882 VL - 72 IS - 16 SP - 3875 EP - 3880 PB - American Chemical Society CY - Washington, DC AN - OPUS4-989 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 -