TY - JOUR A1 - Zientek, Nicolai A1 - Laurain, Clement A1 - Meyer, Klas A1 - Kraume, M. A1 - Guthausen, G. A1 - Maiwald, Michael T1 - Simultaneous 19F-1H medium resolution NMR spectroscopy for online reaction monitoring N2 - Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16'' fluorinated ethylene propylene (FEP) tube with an ID of 0.04'' (1.02 mm) was used as a flow cell in combination with a 5 mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a 1H Larmor frequency of 43.32 MHz and 40.68 MHz for 19F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating 19F and 1H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500 MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16'' FEP tube set-up with an ID of 1.02 mm was characterised regarding the limit of detection (LOQ (1H) = 0.335 mol L-1 and LOQ (19F) = 0.130 mol L-1 for trifluoroethanol in D2O (single scan)) and maximum quantitative flow rates up to 0.3 mL min-1. Thus, a series of single scan 19F and 1H NMR spectra acquired with this simple set-up already presents a valuable basis for quantitative reaction monitoring. KW - NMR KW - 1H KW - 19F KW - Medium-resolution NMR KW - Online NMR KW - Quantitative NMR KW - Reaction monitoring KW - Data processing KW - Process analytical technology PY - 2014 U6 - https://doi.org/10.1016/j.jmr.2014.10.007 SN - 1090-7807 SN - 0022-2364 VL - 249 SP - 53 EP - 62 PB - Elsevier CY - San Diego, Calif. AN - OPUS4-32008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zientek, Nicolai A1 - Meyer, Klas A1 - Dalitz, F. A1 - Kraume, M. A1 - Guthausen, G. A1 - Maiwald, Michael T1 - Neue Möglichkeiten für die Prozessanalytik mit gekoppelter 1H- und 19F-Medium-Resolution-NMR-Spektroskopie N2 - Die Entwicklung innovativer Medium-Resolution-NMR-Spektrometer eröffnet eine Reihe bemerkenswerter Applikationen für die Qualitätskontrolle, die akademische Ausbildung und die Prozessanalytik. Die Verwendung von Permanentmagneten erlaubt den Einsatz der NMR-Spektroskopie in industriellen Prozessumgebungen. KW - NMR KW - 1H KW - 19F KW - Medium-resolution NMR KW - Online NMR KW - Quantitative NMR KW - Reaction monitoring KW - Data processing KW - Process analytical technology KW - IHM KW - PLS PY - 2014 U6 - https://doi.org/10.1002/cite.201450687 SN - 0009-286X SN - 1522-2640 VL - 86 IS - 9 SP - 1575 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-32560 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zientek, Nicolai A1 - Laurain, C. A1 - Meyer, Klas A1 - Paul, Andrea A1 - Engel, D. A1 - Guthausen, G. A1 - Kraume, M. A1 - Maiwald, Michael T1 - Automated data evaluation and modelling of simultaneous F-19-H-1 medium-resolution NMR spectra for online reaction monitoring N2 - Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and processmonitoring. In contrast to high-resolution onlineNMR (HR-NMR),MR-NMRcan be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture fromthe reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by 1H HR-NMR (500MHz) and 1H and 19F MRNMR (43MHz) as amodel system. The parallel online measurement is realised by splitting the flow,which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for 1H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment. KW - NMR KW - 1H-NMR KW - 19F-NMR KW - Medium-resolution NMR KW - Online NMR KW - Quantitative NMR KW - Reaction monitoring KW - Data processing KW - Automation KW - Process analytical technology KW - IHM KW - Indirect hard modeling KW - Chemometrics KW - PLS-R KW - Partial least squares regression PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/mrc.4216/abstract U6 - https://doi.org/doi:10.1002/mrc.4216 VL - 54 SP - 513 EP - 520 PB - John Wiley & Sons, Ltd CY - Hoboken, New Jersey, USA AN - OPUS4-36135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -