Chemie und Prozesstechnik
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Due to the penetration of harmful chlorides into concrete, e.g. from de-icing salt, damage processes such as chloride-related pitting corrosion can occur if critical values are exceeded. In this study, multiphase materials such as chloride-contaminated concrete are examined in detail. A direct comparison is made by analyzing the spectroscopic information of simultaneously measured atomic and molecular emissions with laser-induced breakdown spectroscopy (LIBS). In addition, the influence on the calibration is examined on the basis of the combined spectral information of both reaction paths of the penetrated chlorides. The calibration models of univariate and multivariate methods were validated using reference samples with wet chemical analysis. The results are applied to a concrete sample of a parking deck, which was also analyzed by potentiometric wet chemistry. In order to account for the heterogeneity of concrete, spatially (200 μm) and spectroscopically (0.1 nm) resolved LIBS measurements were performed using a fully automated laboratory system. Simultaneous measurements with three spectrometers allow the analysis of the emission processes of several elements such as Cl, Ca, O, Si and Mg as well as the newly formed molecules CaO and CaCl. The evaluation of the molecular emission in combination with atomic lines extends the analytical performance, since different concrete phases such as aggregates and cement matrix can be better represented. The measurements were carried out in ambient air and with helium purge gas. The limit of detection (LOD) achieved for a combined evaluation of atomic and molecular emission was determined to be 0.028 wt%.
Ein Weg zur wissensbasierten Produktion führt über die Betrachtung der wesentlichen Apparate-, Prozess- und Freigabedaten aus Betrieben und Labors. Das Potenzial dieser Daten wird heute vielfach noch nicht konsequent für ein umfassendes Verständnis der Produktion genutzt.
Neben Fragen zur Datenerfassung, Datenkonnektivität und Datenintegrität müssen solche Daten für eine ganzheitliche Prozessanalyse zunächst mit Kontextinformationen zusammengebracht werden. Datenquellen enthalten vor allem Zeitwertpaare, die numerisch vorbehandelt und möglichst vollautomatisch ausgewertet werden müssen. Am Beispiel NMR-spektroskopischer Daten wird der Stand der Auswertung mit physikalisch motivierten Modellen, wie z. B. dem IHM erläutert.
In 2018, BAM (Federal Institute for Materials Research and Testing) and the young analysts of the department Analytical Chemistry at the Gesellschaft Deutscher Chemiker (German Chemical Society, GDCh) jointly organized the second summer school on quality assurance in analytical chemistry in Berlin, Germany. Over fifty doctoral students that are still in the initial stages of work participated in the week-long event and the participants were confronted with the most important basic concepts of internal and external systems of quality assurance in analytical chemistry.
Especially young scientists and scholars deal with the development of analysis methods and often generate an increasingly growing wealth of data. Results are mostly evaluated under quantitative aspects and need to be assessed subject-specifically. In addition to the purely scientific requirements these results also should meet the requirements of analytical quality assurance. For this purpose, the development of analytical methods is accompanied by a process of validation – the documented proof that a method is suitable for the intended purpose and the defined requirements.
This talk summarizes the didactic concept, which was used by the organizers to span an arc from the handling of process characteristics, such as accuracy, precision, linearity, recovery, up to measurement uncertainty and modern multivariate analysis techniques. In an open space workshop, the participants discussed their idea of quality management and worked out requirements after common sense. Interestingly, many participants had already implemented important quality assurance without professionally knowing it.