TY - INPR A1 - Tchipilov, Teodor A1 - Meyer, Klas A1 - Weller, Michael G. T1 - Quantitative 1H nuclear magnetic resonance (qNMR) of aromatic amino acids for protein quantification N2 - qNMR is a valuable technique for metrological studies due to the uniformity of its signal response for all chemical species of an isotope of interest, which enables compound-independent calibration. However, protein quantification remained challenging as large molecules produce wide, low-intensity signals that reduce the already low sensitivity. Combining qNMR with the hydrolysis of protein samples into amino acids circumvents many of these issues and facilitates the use of NMR spectroscopy for absolute protein and peptide quantification.In this work, different conditions have been tested for quantifying aromatic amino acids and proteins. First, we examined the pH-based signal shifts in the aromatic region. The preferable pH depends on the selection of the amino acids for quantification and which internal standard substance should be used to avoid peak overlap. Several aromatic compounds, such as terephthalic acid, sulfoisophthalic acid, and benzene tricarboxylic acid, have been applied as internal standards. The quantification of amino acids from an amino acid standard, as well as from a certified reference material (bovine serum albumin), was performed. Using the first two suggested internal standards, recovery was ~ 97 % for histidine, phenylalanine, and tyrosine at a concentration of approximately 1 mM in solution. Acidic hydrolysis of a certified reference material (CRM) of bovine serum albumin (BSA) and subsequent quantification of Phe and Tyr yielded recoveries of 98 ± 2 and 88 ± 4 %, respectively, at a protein concentration of 16 g/L or 250 µM. KW - Amino acid analysis KW - AAA KW - Protein hydrolysis KW - Metrology KW - Traceability KW - Reference materials KW - Internal standards KW - Calibration PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564520 DO - https://doi.org/10.20944/preprints202211.0569.v1 SP - 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-56452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tchipilov, Teodor A1 - Meyer, Klas A1 - Weller, Michael G. T1 - Quantitative 1H nuclear magnetic resonance (qNMR) of aromatic amino acids for protein quantification N2 - Hydrolysis of protein samples into amino acids facilitates the use of NMR spectroscopy for protein and peptide quantification. Different conditions have been tested for quantifying aromatic amino acids and proteins. The pH-dependent signal shifts in the aromatic region of amino acid samples were examined. A pH of 12 was found to minimize signal overlap of the four aromatic amino acids. Several aromatic compounds, such as terephthalic acid, sulfoisophthalic acid, and benzene tricarboxylic acid, were applied as internal standards. The quantification of amino acids from an amino acid standard was performed. Using the first two suggested internal standards, recovery was ~97% for histidine, phenylalanine, and tyrosine at a concentration of approximately 1 mM in solution. Acidic hydrolysis of a certified reference material (CRM) of bovine serum albumin (BSA) and subsequent quantification of Phe and Tyr yielded recoveries of 98% ± 2% and 88% ± 4%, respectively, at a protein concentration of 16 g/L or 250 µM. KW - Amino acid analysis KW - Aromatic amino acid analysis KW - AAA KW - AAAA KW - Protein hydrolysis KW - Hydrochloric acid KW - Metrology KW - Traceability KW - NIST KW - Reference materials KW - Internal standard KW - Calibration KW - Compound-independent calibration KW - Histidine KW - Tyrosine KW - Tryptophan KW - Phenylalanine KW - Terephthalic acid KW - Benzene-1,3,5-tricarboxylic acid KW - Bovine serum albumin (BSA) KW - Quantitative protein analysis KW - Phenylketonuria PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570943 DO - https://doi.org/10.3390/mps6010011 VL - 6 IS - 1 SP - 1 EP - 13 PB - MDPI CY - Basel, Schweiz AN - OPUS4-57094 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bernstein, Michael A1 - Diehl, Bernd W. K. A1 - Holzgrabe, Ulrike A1 - Maiwald, Michael A1 - Meyer, Klas A1 - Monakhova, Yulia A1 - Schönberger, Torsten T1 - qNMR - The handbook N2 - Quantitative NMR (qNMR) has been around for a long time, but also has great potential to solve future problems in any quantitative analysis. As a primary method, it differs fundamentally from chromatographic methods: it is better described as a quantum mechanical balance. Succesful implementation of qNMR requires certain attention to detail. "qNMR - the handbook" is intended to be a guide for analysts to help understand the fundamental principles of NMR and the significant points relating to its implementation for quantitation. Regulatory considerations of qNMR adoption are explained. NMR fundamentals are explained to provide understanding. Together with many useful examples, the book is a compelling addition to the laboratory's reference library, providing all the tools that any practitioner should know to successfully implement qNMR. The authors are qNMR pioneers and come from a variety of backgrounds including business, government and academia. KW - Quantitative NMR spectroscopy KW - NMR spectroscopy KW - Handbook KW - qNMR PY - 2023 SN - 978-3-7568-7891-8 SN - 978-3-7583-8050-1 SP - 1 EP - 302 PB - BoD – Books on Demand CY - Norderstedt AN - OPUS4-59839 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruno, Francesco A1 - Fiorucci, Letizia A1 - Vignoli, Alessia A1 - Meyer, Klas A1 - Maiwald, Michael A1 - Ravera, Enrico T1 - pyIHM: Indirect Hard Modeling, in Python N2 - NMR is a powerful analytical technique that combines an exquisite qualitative power, related to the unicity of the spectra of each molecule in a mixture, with an intrinsic quantitativeness, related to the fact that the integral of each peak only depends on the number of nuclei (i.e., the amount of substance times the number of equivalent nuclei in the signal), regardless of the molecule. Signal integration is the most common approach in quantitative NMR but has several drawbacks (vide infra). An alternative is to use hard modeling of the peaks. In this paper, we present pyIHM, a Python package for the quantification of the components of NMR spectra through indirect hard modeling, and we discuss some numerical details of the implementation that make this approach robust and reliable. KW - Algorithms KW - Chemical Structure KW - Deconvolution KW - Mixtures KW - NMR spectroscopy PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626793 DO - https://doi.org/10.1021/acs.analchem.4c06484 SN - 1520-6882 VL - 97 IS - 8 SP - 4598 EP - 4605 PB - ACS Publications CY - Washington D.C. AN - OPUS4-62679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Klas T1 - Process Monitoring with Compact NMR spectroscopy: Applications from Lab to Field N2 - The use of compact NMR instruments based on permanent magnets has been increasing in recent years. Their affordability, portability, and ease of operation without the need for trained staff make them particularly interesting for quality control application in industrial production. Recent developments by instrument manufacturers, such as multi-nuclei options or extended interfacing, have made these systems even more versatile. However, the application of NMR spectroscopy as an online PAT tool remains rare, despite its significant potential for process optimization and control. A key challenge in exploiting this potential is the integration of lab instruments into the harsh environment of a chemical plant. Additionally, advancements in automation and data evaluation are key tasks to ensure robust, unattended operation with minimal maintenance requirements. In this presentation, we showcase examples of using NMR spectroscopy for process monitoring at the lab scale, the development of open-source software tools for NMR data evaluation (PyIHM, within the Python package KLASSEZ), and a successful example of field integration, running an automated laboratory instrument in the environment of a industrial production plant. T2 - Quantitative NMR Methods for Reaction and Process Monitoring (NMRPM) CY - Kaiserslautern, Germany DA - 31.03.2025 KW - Compact NMR spectroscopy KW - Process Monitoring KW - Downstream processing KW - Indirect Hard Modeling KW - Field integration PY - 2025 AN - OPUS4-62850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Klas T1 - Online-NMR- und -Raman-Spektroskopie – Kombination von PAT-Methoden für mehr Prozessverständnis N2 - Die Verbesserung des Prozessverständnisses ist eine notwendige Voraussetzung für die Anwendung von Konzepten wie „Industrial Internet of Things (IIoT)“ oder „Industrie 4.0“. Online-Methoden der Prozessanalytik (PAT) ermöglichen die direkte Verfolgung der ablaufenden Reaktionen innerhalb chemischer und pharmazeutischer Produktionsschritte und können somit einen wichtigen Beitrag für die Entwicklung von neuen, innovativen Prozessführungsstrategien liefern. Während die Online-Raman-Spektroskopie bereits erfolgreich im industriellen Umfeld zum Einsatz kommt, ist der Entwicklungsstand für die Online-Niederfeld-NMR-Spektroskopie bislang noch nicht ausreichend für einen routinemäßigen Einsatz innerhalb industrieller Produktionsumgebungen. Der hohe Informationsgehalt der NMR-Daten in Verbindung mit einem geringen Kalibrieraufwand macht die Methode sehr interessant für moderne Konzepte flexibler Produktionsanlagen für die Herstellung vieler unterschiedlicher Produkte in wechselnden Kampagnen. Speziell in modularen Produktionskonzepten kann so die Rüstzeit der Prozessanalytik deutlich verkürzt werden. Am Beispiel der heterogen katalysierten Hydrogenierung von 2-Butin-1,4-diol wird der Einsatz der Kombination von Online-NMR und -Raman-Spektroskopie demonstriert. Dieser Prozessschritt aus der industriellen Synthese des Lösungsmittels Tetrahydrofuran verläuft über ein Zwischenprodukt, welches konkurrierende Reaktionspfade aufweist. Die Kombination von Informationen aus der PAT, sowie von klassischen Prozessgrößen, wie Druck, Temperatur und Durchfluss in einem hoch automatisierten Aufbau erleichtert die Entwicklung und Erprobung von neuen Konzepten für die Prozessführung. T2 - 10. ProcessNet-Jahrestagung CY - Online meeting DA - 21.09.2020 KW - Hydrogenierung KW - Benchtop-NMR KW - Raman-Spektroskopie KW - Prozessanalytik PY - 2020 AN - OPUS4-51363 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Klas T1 - Online-NMR Spektroskopie in der PAT - Entwicklungen zwischen Labor- und Feldeinsatz N2 - Die NMR-Spektroskopie ist eine der zentralen nicht-invasiven Analysenmethoden in der organischen Chemie und aus dem Laboralltag nicht mehr wegzudenken. Die direkte Proportionalität zwischen der Anzahl der Atomkerne im Messvolumen und der Signalfläche im Spektrum ist vergleichbar mit einem „Zählen der Kernspins“. Der Kalibrieraufwand für die Quantifizierung ist minimal und aus dem NMR-Spektrum sind Informationen zu Struktur und Identität zugänglich. Online-NMR-Spektroskopie wird unter Zuhilfenahme von speziellen Durchflussproben-köpfen und Messzellen bereits seit Jahrzehnten erforscht und eingesetzt. Durch die hohen Anforderungen an die Aufstellung und den Betrieb von klassischen Hochfeld-NMR-Spektrometern konnte sie allerdings nie den Sprung vom Labor in den Prozess schaffen. Dies hat sich durch die Entwicklungen im Bereich mobil einsetzbarer Benchtop-NMR-Spektrometer grundlegend verändert. Geringere Investitions- und Betriebskosten, sowie die Robustheit und einfache Bedienbarkeit dieser Systeme sind entscheidende Faktoren. Damit rückt eine Anwendung als Online-PAT-Methode technisch in greifbare Nähe. Designierte Prozess-NMR-Spektrometer sucht man heutzutage allerdings auf dem Markt meist noch vergebens. Die Reaktionsverfolgung im Labormaßstab konnte an unterschiedlichen Systemen erfolgreich demonstriert werden. Dabei zeigten sich allerdings Limitierungen in Hinblick auf einen möglichen Prozesseinsatz. Insbesondere die Temperaturempfindlichkeit der Magnetsysteme ist hier zu nennen. Anhand eines Prototyps wurde eine aktive Temperaturisolation mittels temperierter Luftströmungen entwickelt und erprobt. Eine Feldintegration von Laborsystemen geht sowohl technisch als auch regulatorisch mit zahlreichen Herausforderungen einher. Das raue Umfeld von Produktionsanlagen, sowie die Anforderungen an Explosionsschutz erfordern eine zugelassene Einhausung. Auf Basis von Erfahrungen mit einem ersten Prototyp erfolgte die gemeinsame Entwicklung eines möglichst flexibel einsetzbaren Analysenschranks. Neben der Hardware-Integration sind die automatisierte modellbasierte Auswertung der NMR-Spektren, sowie die Einbindung in die Prozessleittechnik essenziell für einen zuverlässigen Betrieb als PAT-Analysengerät. T2 - 18. Kolloquium AK Prozessanalytik CY - Krefeld, Germany DA - 27.11.2023 KW - Prozessanalytik KW - Online-NMR-Spektroskopie KW - NMR-Spektroskopie KW - Benchtop-NMR KW - Feldintegration PY - 2023 AN - OPUS4-58969 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Klas T1 - On-line monitoring of polyhydroxyalkanoate extraction process using compact NMR spectroscopy N2 - Portable benchtop NMR spectrometers enable real-time process and reaction monitoring in contrast to conventional laboratory based off-line gas chromatography or high-field NMR measurements. In this study, benchtop NMR spectroscopy is demonstrated as a process analytical technology (PAT) tool for the application of the solvent extraction step in downstream processing of polyhydroxyalkanoate (PHA) biopolymers. These are one of the few thermoplastic polymers synthesized 100 % via biotechnological routes which fully biodegrade in common natural environments. This makes them excellent candidate materials for sustainable replacement of conventional plastic materials. Online NMR experiments were conducted using a fully automated setup, employing commercially available PTFE tubing as a flow-cell assembly. Extraction was carried out in a thermostated stirred batch reactor in lab-scale. Single-scan NMR spectra allowed continuous monitoring of the extraction of the PHA copolymer poly(hydroxybutyrate-co-hydroxyhexanoate) containing 13.5 mol-% hydroxyhexanoate from Ralstonia eutropha biomass. Extractions were performed in chloroform and acetone across lyophilized cell loadings ranging from 20 to 120 g/L. The reproducibility and reliability of compact NMR spectroscopy closely matched that of parallel high-field NMR measurements. A strong correlation was observed between online low-field NMR data and offline gas chromatography (GC) analysis. The study highlights the versatility of compact NMR for process monitoring, facilitating endpoint determination and enhancing extraction efficiency by optimizing process parameters. Steady-state conditions were achieved within 6 to 10 minutes for chloroform and acetone, respectively, underscoring the method’s value in supporting downstream process development and optimization for PHA recovery. T2 - qNMR Summit Europe 2025 CY - Bari, Italy DA - 19.11.2025 KW - NMR Spectroscopy KW - Extraction KW - Downstream processing KW - Benchtop-NMR PY - 2025 AN - OPUS4-64920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Klas T1 - On-line monitoring of polyhydroxyalkanoate extraction process using compact NMR spectroscopy N2 - Portable benchtop NMR spectrometers enable real-time process and reaction monitoring in contrast to conventional laboratory based off-line gas chromatography or high-field NMR measurements. In this study, benchtop NMR spectroscopy is demonstrated as a process analytical technology (PAT) tool for the application of the solvent extraction step in downstream processing of polyhydroxyalkanoate (PHA) biopolymers. These are one of the few thermoplastic polymers synthesized 100 % via biotechnological routes which fully biodegrade in common natural environments. This makes them excellent candidate materials for sustainable replacement of conventional plastic materials. Online NMR experiments were conducted using a fully automated setup, employing commercially available PTFE tubing as a flow-cell assembly. Extraction was carried out in a thermostated stirred batch reactor in lab-scale. Single-scan NMR spectra allowed continuous monitoring of the extraction of the PHA copolymer poly-(hydroxybutyrate-co-hydroxyhexanoate) containing 13.5 mol-% hydroxyhexanoate from Ralstonia eutropha biomass. Extractions were performed in chloroform and acetone across ground lyophilized cell loadings ranging from 20 to 120 g/L. The reproducibility and reliability of compact NMR spectroscopy closely matched with high-field NMR measurements. A strong correlation was observed between online low-field NMR data and offline gas chromatography (GC) analysis. The study highlights the versatility of compact NMR for process monitoring, facilitating endpoint determination and enhancing extraction efficiency by optimizing process parameters. Steady-state conditions were achieved within 6 to 10 minutes for chloroform and acetone, respectively, underscoring the method’s value in supporting downstream process development and optimization for PHA recovery. T2 - 20. Herbstkolloquium Arbeitskreis Prozessanalytik CY - Frankfurt am Main, Germany DA - 03.12.2025 KW - Polyhydroxyalkanoate KW - Process Analytical Technology KW - Downstream processing KW - Benchtop-NMR PY - 2025 AN - OPUS4-65065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiele, Isabel A1 - Weiske, Björn A1 - Riedel, Sebastian L. A1 - Meyer, Klas T1 - On-line monitoring of polyhydroxyalkanoate extraction by low-field nuclear magnetic resonance spectroscopy N2 - The use of low-field nuclear magnetic resonance (NMR) spectroscopy enables real-time reaction monitoring in contrast to time-consuming gas chromatography or off-line high-field NMR measurements. In this study, NMR spectroscopy is demonstrated as a novel process analytical technology (PAT) tool in the downstream processing of polyhydroxyalkanoate (PHA) biopolymers. On-line NMR spectroscopy measurements were performed using a Spinsolve 43 Carbon Ultra instrument in a fully automated mode with a flow-assembly based on PTFE tubing. Single-scan NMR spectra were acquired for real-time monitoring of the extraction process of the PHA copolymer poly(hydroxybutyrate-co-hydroxyhexanoate) with 13.5 mol.% hydroxyhexanoate [P(HB-co-13.5 mol.%HHx)] from Ralstonia eutropha biomass using chloroform or acetone as PHA solvents at lyophilized cell loadings of 20–120 g L􀀀 1. The reproducibility and reliability of low-field NMR spectroscopy was comparable to high-field NMR spectroscopy, with superior performance in terms of time. The correlation between the results of on-line monitoring using low-field NMR spectroscopy and off-line analysis using gas chromatography (GC) showed a correlation coefficient of >94 %. The versatility of low-field NMR spectroscopy for elucidating reaction kinetics, facilitating endpoint determination and accelerating extraction processes by maximizing solubility is highlighted as plateau values were reached within 6–10 min for chloroform and acetone, respectively. This novel low-field NMR spectroscopy application promotes a new monitoring approach for downstream PHA processing and supports process development and optimization. KW - Polyhydroxyalkanoate KW - Extraction KW - NMR KW - Ralstonia eutropha KW - Downstream processing PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624215 DO - https://doi.org/10.1016/j.polymdegradstab.2025.111188 SN - 1873-2321 VL - 233 SP - 1 EP - 10 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-62421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -