Overhauser DNP with Benchtop NMR Spectrometer for Process Monitoring

The goal of this project is to improve the sensitivity of benchtop NMR experiments on liquid samples by amplifying the signal using Overhauser Dynamic Nuclear Polarization (ODNP). ODNP is a method for enhancing the NMR signal in which the high polarization of unpaired electrons is transferred to neighboring atomic nuclei. This is achieved by irradiating the sample with microwaves that excite electron spin transitions. The method is based on the Overhauser effect and results in a significant amplification of the nuclear spin polarization—and thus of the NMR signal—particularly at low magnetic fields. Stable radicals are typically used as a source of unpaired electrons. The use of ODNP enables time-resolved measurements even at very low analyte concentrations or in small sample volumes, such as in microcapillaries. This makes the technique particularly attractive for process engineering applications. Due to the short time scales at which ODNP operates, it is also ideally suited for the continuous hyperpolarization of fast-flowing liquids.

Benchtop NMR for Assessing the Quality of Grapes for Winemaking

In wineries, reliable and rapid analysis of incoming grapes is of great importance. Among other things, these grapes must be tested for sugar and acid content as well as rot indicators. These analytical values are typically determined using FT-IR spectroscopy. However, this measurement method has drawbacks, as it not only exhibits significant measurement uncertainties but also requires regular calibration using reference values. NMR spectroscopy offers advantages over FT-IR because it provides higher resolution and enables direct quantification of the signals. Benchtop NMR spectrometers are comparatively cost-effective and very compact devices that can play an important role in such applications. One challenge in using benchtop NMR spectrometers is reducing the comparatively long measurement time without compromising sensitivity. To compensate for the lower resolution and sensitivity of benchtop NMR devices compared to conventional NMR spectrometers, a mathematical analysis method based on a quantum mechanical model was developed. The goal of the project is to extend this analysis method for use with other components present in very low concentrations. 

Teaching Assistance

• Anwendung der Magnetresonanz für Naturwissenschaftler und Ingenieure (WS 2024/2025)
• Grundlagenlabor für das Schwerpunktfach I (SS 2025)
• BCI - Einführung in experimentelles Arbeiten (SS2025)
• Elektrolytthermodynamik (WS 2025/2026)
• Elektrochemische Energiespeicherung (SS2026)

Appointments

Inquire by E-Mail

Publications

• B. Salgado, J. Lueck, G. Heinrich, P. Nickolaus, U. Fischer, D. J. Holland, F. Jirasek, H. Hasse, L. Keller, K. Münnemann: pH Determination in Grape Must by Benchtop NMR Spectroscopy (https://doi.org/10.1002/cfch.70035) ChemFoodChem, (2026) e70035.

Presentations

• B. Salgado, J. Phuong, S. Mross, H. Hasse, K. Münnemann: Quantitative Analysis using ODNP-Enhanced ¹³C Benchtop NMR Spectroscopy for Continuous-Flow Applications. qNMR Summit, Bari, 19.11-21.11.2025.
• B. Salgado, J. Lueck, G. Heinrich, P. Nickolaus, U. Fischer, L. Keller, D. Holland, F. Jirasek, H. Hasse, K. Münnemann: Benchtop NMR for Grape Juice Quality Assessment and Fermentation Monitoring. Food Chemistry and Technology, Rom, 15.10-17.10.2025
• B. Salgado, J. Phuong, S. Mross, H. Hasse, K. Münnemann: ODNP-Enhanced Benchtop ¹³C NMR Spectroscopy for Continuous-Flow Applications. µscale NMR and MRI Conference, Ettlingen, 29.06-02.07.2025

Posters

• B. Salgado, S. Mross, H. Hasse, K. Münnemann: Overhauser Dynamic Nuclear Polarization for Multi-Nuclear Signal Enhancement in Continuous-Flow. European Magnetic Resonance Congress, Göteborg, 29.06.-02.07.2026
• B. Salgado, J. Phuong, S. Mross, H. Hasse, K. Münnemann: Quantitative Continuous-Flow Benchtop NMR Enabled by Overhauser DNP.  Small Molecule NMR Conference, Porto, 21.09-24.09.2025
• B. Salgado, J. Phuong, S. Mross, H. Hasse, K. Münnemann: ODNP-Enhanced Benchtop ¹³C NMR Spectroscopy for Continuous-Flow Applications. µscale NMR and MRI Conference, Ettlingen, 29.06-02.07.2025
• B. Salgado, J. Phuong, S. Mross, H. Hasse, K. Münnemann: Overhauser Dynamic Nuclear Polarization for Quantitative Benchtop NMR Spectroscopy in Continuous Flow . NMRPM, Kaiserslautern, 31.03-02.04.2025
• B. Salgado, J. Phuong, J. Lueck, P. Nickolaus, U. Fischer, L. Keller, D. Holland, H. Hasse, F. Jirasek, K. Münnemann: Benchtop NMR Approach for Grape Analysis and Real-time Fermentation Monitoring . NMRPM, Kaiserslautern, 31.03-02.04.2025
• B. Salgado, J. Phuong, J. Lueck, P. Nickolaus, U. Fischer, L. Keller, D. Holland, H. Hasse, F. Jirasek, K. Münnemann: Online Process Monitoring of Wine Fermentation by NMR Spectrscopy. Thermodynamik Kolloquium, Stuttgart, 25.-27.07.2024
• B. Salgado, J. Phuong, J. Lueck, P. Nickolaus, U. Fischer, L. Keller, D. Holland, H. Hasse, F. Jirasek, K. Münnemann: Benchtop NMR Spectroscopy for Quantitative Analysis of Grapes for Wine Production. qNMR SUMMIT, Buchs, 18.-20.09.2024
• B. Salgado, S. Passlack, S. Ehnert, M. Kopnarski: Quantitative Analysis of the Hydrogen Concentration on Surfaces using SNMS. Conference on Applied Surface and Solid Material Analysis, Zürich, 11.-13.09.2023