Person: Rapp, Thomas
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Veröffentlichung Release of antioxidants and their degradation products from materials in contact with drinking water(2023) Berger, Sabrina; Kalweit, Cynthia; Kämpfe, Alexander David; Rapp, ThomasVeröffentlichung Quantification and stability assessment of 7,9-di.tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione leaching from cross-linked polyethylene pipes using gas and liquid chromatography(2023) Berger, Sabrina; Kalweit, Cynthia; Kämpfe, Alexander David; Rapp, ThomasThis study assesses the formation and stability of the water contaminant 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione ([1]) which repeatedly occurs in the migration waters of cross-linked polyethylene (PE-X) pipes. In aqueous solution [1] is partially transformed to 3-(3,5-di-tert-butyl-1-hydroxy-4-oxo-2,5-cyclohexadien-1-yl)propionic acid ([2]). For a better understanding of the formation of [1] and its transformation into [2] an analytical method was established to allow the analysis of both species separately. Because of thermal instability [2] cannot be detected with GC-MS. Therefore, two methods were validated for a reliable and reproducible quantification: GC-MS for [1] and HPLC-MS/MS for both [1] and [2]. Comparative measurements of migration waters from PE-X pipes using GC-MS and HPLC-MS/MS methods showed that the concentrations of [1] detected with GC-MS corresponds to the sum of [1] and [2] measured with HPLC-MS/MS. In the migration waters [1] was detected in higher concentrations than [2]. The highest concentrations of [1], detected with GC-MS, were > 300 (micro)g/L. The longer the materials are stored without contact with water, the more [1] is measured in the migration waters. Most of the previous values reported in the literature for [1] were based on semi-quantification. Hence, we compared results of the semi-quantitative determination according to EN 15768 with those of a quantitative method with a standard. The results gained with the semi-quantitative method represent less than 50% of the quantified values for the amount leaching from the pipes, which means that the semi-quantification method according to EN 15768 leads to a significant underestimation of [1]. Finally, stability assessment showed that [1] developed an equilibrium with [2] under acidic conditions, whereas it will completely be transferred to [2] at pH 10. At pH 7, it takes more than 50 days for [1] to reach an equilibrium with [2]. However, at increasing the temperature to 60 ËÌC, [1] will be rapidly transformed into [2]. Besides [1] and [2], other currently unknown degradation products are formed. As there is no comprehensive toxicological assessment for both substances available today, our findings underline the need for regulatory consequences. © 2023 Elsevier Ltd. All rights reserved.Veröffentlichung Trinkwasser aus dem Hahn(Umweltbundesamt, 2020) Berger, Sabrina; Böhme, Ilka; Brunner, Claudia; Förster, Christina; Grope, Norbert; Mohaupt, Juliane; Oppelt, Angela; Rapp, Thomas; Schuster, Ramona; Steinel, Katrin; Deutschland. UmweltbundesamtSchon seine Definition ist klar: Trinkwasser ist alles Wasser, das im häuslichen Bereich zum Trinken und für andere Lebensmittelzwecke, zur Körperpflege und -reinigung sowie zur Reinigung von Gegenständen, die nicht nur vorübergehend mit Lebensmitteln oder dem menschlichen Körper in Kontakt kommen, bestimmt ist. Quelle: https://www.umweltbundesamt.deVeröffentlichung Anforderungen an Materialien und Werkstoffe im Kontakt mit Trinkwasser(2014) Berger, Sabrina; Rapp, Thomas