NMR-based isotopic and isotopomic analysis.

1. Prog Nucl Magn Reson Spectrosc. 2020 Oct-Dec;120-121:1-24. doi: 10.1016/j.pnmrs.2020.07.001. Epub 2020 Jul 15. NMR-based isotopic and isotopomic analysis. Akoka S(1), Remaud GS(2). Author information: (1)Université de Nantes, CNRS, CEISAM, UMR 6230, F-44000 Nantes, France. Electronic address: serge.akoka@univ-nantes.fr. (2)Université de Nantes, CNRS, CEISAM, UMR 6230, F-44000 Nantes, France. Electronic address: gerald.remaud@univ-nantes.fr. Molecules exist in different isotopic compositions and most of the processes, physical or chemical, in living systems cause selection between heavy and light isotopes. Thus, knowing the isotopic fractionation of the common atoms, such as H, C, N, O or S, at each step during a metabolic pathway allows the construction of a unique isotope profile that reflects its past history. Having access to the isotope abundance gives valuable clues about the (bio)chemical origin of biological or synthetic molecules. Whereas the isotope ratio measured by mass spectrometry provides a global isotope composition, quantitative NMR measures isotope ratios at individual positions within a molecule. We present here the requirements and the corresponding experimental strategies to use quantitative NMR for measuring intramolecular isotope profiles. After an introduction showing the historical evolution of NMR for measuring isotope ratios, the vocabulary and symbols - for describing the isotope content and quantifying its change - are defined. Then, the theoretical framework of very accurate quantitative NMR is presented as the principle of Isotope Ratio Measurement by NMR spectroscopy, including the practical aspects with nuclei other than 2H, that have been developed and employed to date. Lastly, the most relevant applications covering three issues, tackling counterfeiting, authentication, and forensic investigation, are presented, before giving some perspectives combining technical improvements and methodological approaches. Copyright © 2020 Elsevier B.V. All rights reserved. DOI: 10.1016/j.pnmrs.2020.07.001 PMID: 33198965 Conflict of interest statement: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.