page_title: Isotopic analysis by nuclear magnetic resonance
section_title: Isotopic distribution
hierarchical_section_title: Isotopic analysis by nuclear magnetic resonance / Principle / Isotopic distribution
caption_attribution_description: English: Natural existence of hydrogen, carbon and oxygen
context_page_description: Isotopic analysis by nuclear magnetic resonance allows the user to quantify with great precision the differences of isotopic contents on each site of a molecule and thus to measure the specific natural isotope fractionation for each site of this molecule. The SNIF-NMR analytical method was developed to detect the sugaring of wine and enrichment of grape musts, and is mainly used to check the authenticity of foodstuffs and to control the naturality of some aromatic molecules. The SNIF-NMR method has been adopted by the International Organisation of Vine and Wine and the European Union as an official method for wine analysis. It is also an official method adopted by the Association Of Analytical Chemists for analysis of fruit juices, maple syrup, vanillin, and by the European Committee for Standardization for vinegar.
context_section_description: The atoms hydrogen, oxygen, and carbon co-exist naturally in specific proportions with their stable isotopes, 2H (or D), 18O and 13C respectively, in different proportions as shown in the figure 2 below.
  The amount and distribution of the different isotopes in a molecule is influenced by: 
  Environmental (climatic and geographical) conditions - for natural products
  Chemical or biochemical processes such as the photosynthetic metabolism in plants
  This phenomenon is known as natural isotopic fractionation (see Figure 3). The resulting isotopic fingerprint can provide information on the origin - botanical, synthetic, geographical - of the molecule or product.
caption: Figure 2
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