Determination of self-diffusion coefficients in mixtures with benchtop 13 C NMR spectroscopy via polarization transfer.

Autor: Phuong J; Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany., Mross S; Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany., Bellaire D; Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany., Hasse H; Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany., Münnemann K; Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany.
Jazyk: angličtina
Zdroj: Magnetic resonance in chemistry : MRC [Magn Reson Chem] 2024 May; Vol. 62 (5), pp. 386-397. Date of Electronic Publication: 2023 Nov 28.
DOI: 10.1002/mrc.5412
Abstrakt: Nuclear magnetic resonance (NMR) is an established method to determine self-diffusion coefficients in liquids with high precision. The development of benchtop NMR spectrometers makes the method accessible to a wider community. In most cases, 1 H NMR spectroscopy is used to determine self-diffusion coefficients due to its high sensitivity. However, especially when using benchtop NMR spectrometers for the investigation of complex mixtures, the signals in 1 H NMR spectra can overlap, hindering the precise determination of self-diffusion coefficients. In 13 C NMR spectroscopy, the signals of different compounds are generally well resolved. However, the sensitivity of 13 C NMR is significantly lower than that of 1 H NMR spectroscopy leading to very long measurement times, which makes diffusion coefficient measurements based on 13 C NMR practically infeasible with benchtop NMR spectrometers. To circumvent this problem, we have combined two known pulse sequences, one for polarization transfer from 1 H to the 13 C nuclei (PENDANT) and one for the measurement of diffusion coefficients (PFG). The new method (PENPFG) was used to measure the self-diffusion coefficients of three pure solvents (acetonitrile, ethanol and 1-propanol) as well as in all their binary mixtures and the ternary mixture at various compositions. For comparison, also measurements of the same systems were carried out with a standard PFG-NMR routine on a high-field NMR instrument. The results are in good agreement and show that PENPFG is a useful tool for the measurement of the absolute value of the self-diffusion coefficients in complex liquid mixtures with benchtop NMR spectrometers.
(© 2023 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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