TY - JOUR A1 - Spallanzani, Roberta A1 - Koga, K. A1 - Cichy, S. A1 - Wiedenbeck, M. A1 - Schmidt, B. A1 - Oelze, Marcus A1 - Wilke, M. T1 - Lithium and boron difusivity and isotopic fractionation in hydrated rhyolitic melts N2 - Lithium and boron are trace components of magmas, released during exsolution of a gas phase during volcanic activity. In this study, we determine the difusivity and isotopic fractionation of Li and B in hydrous silicate melts. Two glasses were synthesized with the same rhyolitic composition (4.2 wt% water), having diferent Li and B contents; these were studied in difusion-couple experiments that were performed using an internally heated pressure vessel, operated at 300 MPa in the temperature range 700–1250 °C for durations from 0 s to 24 h. From this we determined activation energies for Li and B difusion of 57±4 kJ/mol and 152±15 kJ/mol with pre-exponential factors of 1.53 × 10–7 m2/s and 3.80× 10–8 m2 /s, respectively. Lithium isotopic fractionation during difusion gave β values between 0.15 and 0.20, whereas B showed no clear isotopic fractionation. Our Li difusivities and isotopic fractionation results difer somewhat from earlier published values, but overall confrm that Li difusivity increases with water content. Our results on B difusion show that similarly to Li, B mobility increases in the presence of water. By applying the Eyring relation, we confrm that B difusivity is limited by viscous fow in silicate melts. Our results on Li and B difusion present a new tool for understanding degassing-related processes, ofering a potential geospeedometer to measure volcanic ascent rates. KW - Hydrated silicate melts KW - Stable isotopes KW - Diffusion KW - Isotopic fractionation PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-554496 DO - https://doi.org/10.1007/s00410-022-01937-2 VL - 177 IS - 8 SP - 1 EP - 17 PB - Springer AN - OPUS4-55449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zweigle, J. A1 - Schmidt, A. A1 - Bugsel, B. A1 - Vogel, Christian A1 - Simon, Fabian A1 - Zwiener, C. T1 - Perfluoroalkyl acid precursor or weakly fluorinated organic compound? A proof of concept for oxidative fractionation of PFAS and organofluorines N2 - Organofluorine mass balance approaches are increasingly applied to investigate the occurrence of per- and polyfluoroalkyl substances (PFAS) and other organofluorines in environmental samples more comprehensively. Usually, complex samples prevent the identification and quantification of every fluorine-containing molecule. Consequently, large unidentified fractions between fluorine sum parameters such as extractable organic fluorine (EOF) and the sum of quantified analytes are frequently reported. We propose using oxidative conversion to separate (unidentified) weakly fluorinated compounds (e.g., pesticides, pharmaceuticals) from PFAA-precursors (perfluoroalkyl chain lengths ≥ C6). We show with three organofluorine model substances (flufenamic acid, diflufenican, pantoprazole) that CF3-groups or aromatic fluorine can be quantitatively converted to inorganic fluoride and trifluoroacetic acid (TFA) by applying PhotoTOP oxidation (UV/TiO2). The principle of fluorine separation in mixtures is demonstrated by the oxidation of the three weakly fluorinated compounds together with the PFAA-precursor 6:2/6:2 fluorotelomer mercaptoalkyl phosphate diester (FTMAP). After oxidation, the products F− and TFA were separated from PFCAs ( C4) by SPE, and the fractions were analyzed individually. Closed mass balances both with and without the addition of organic matrix were achieved. Eventually, the fluorine balance was verified by total fluorine measurements with combustion ion chromatography (CIC). The proposed methods should be considered a proof of concept to potentially explain unidentified fractions of the EOF, especially if compounds with low fluorine content such as pesticides, pharmaceuticals, and their transformation products contribute largely to the EOF. Future studies are needed to show the applicability to the complexity of environmental samples. Graphical Abstract KW - Combustion Ion Chromatography KW - Per- and Polyfluoroalkyl substances (PFAS) PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613429 DO - https://doi.org/10.1007/s00216-024-05590-5 SP - 1 EP - 10 PB - Springer Science and Business Media LLC AN - OPUS4-61342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -