title: The new face of isotopic NMR at natural abundance.
abstract: The most widely used method for isotope analysis at natural abundance is isotope ratio monitoring by Mass Spectrometry (irm-MS) which provides bulk isotopic composition in2H,13C,15N,18O or34S. However, in the 1980s, the direct access to Site-specific Natural Isotope Fractionation by Nuclear Magnetic Resonance (SNIF-NMRTM) was immediately recognized as a powerful technique to authenticate the origin of natural or synthetic products. The initial - and still most popular - application consisted in detecting the chaptalization of wines by irm-2H NMR. The approach has been extended to a wide range of methodologies over the last decade, paving the way to a wide range of applications, not only in the field of authentication but also to study metabolism. In particular, the emerging irm-13C NMR approach delivers direct access to position-specific13C isotope content at natural abundance. After highlighting the application scope of irm-NMR (2H and13C), this article describes the major improvements which made possible to reach the required accuracy of 1‰ (0.1%) in irm-13C NMR. The last part of the manuscript summarizes the different steps to perform isotope analysis as a function of the sample properties (concentration, peak overlap) and the kind of targeted isotopic information (authentication, affiliation). Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France.
authors.forename: Tangi
authors.initials: T
authors.lastname: Jézéquel
authors.affiliation: Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Joubert
authors.affiliation: Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France.|Institut Universitaire de France, Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Giraudeau
authors.affiliation: Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France.
authors.forename: Gérald S
authors.initials: GS
authors.lastname: Remaud
authors.affiliation: Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Akoka
keywords: Position-Specific Isotope Analysis; SNIF-NMR; internal standard; irm-NMR; isotope analysis