Recent advances in site-specific natural isotope fractionation studied by nuclear magnetic resonance

Site-specific Natural Isotopic Fractionation of hydrogen and carbon in nicotine, glycerol and vanillin was studied by NMR spectroscopy (SNIF-NMR) in order to point out specific mechanistic and environmental effects. Several products (cellulose, sugars, acids, nicotine) isolated from tobacco leaves present related carbon and nitrogen fractionation profiles. In nicotine, it is possible to measure eleven site-specific isotope ratios (D/H)(t) which give useful information about the climate of the region of production. The origin of glycerol in fermented beverages can be determined by H-2 and C-13-NMR, and the botanical origin of triglycerides can also be checked in the same way. Vanillin is a typical example of aroma which has undergone a series of sophisticated adulterations but which can be authentifred by isotopic NMR techniques. The whole population of vanillin molecules can be split into more and more diversified sub-groups by H-2 and C-13 SNIF-NMR.