title: NMR approach to the quantification of nonstatistical 13C distribution in natural products: vanillin.
abstract: Quantitative (13)C NMR conditions have been established that permit the precise determination of site-specific (13)C/(12)C ratios at low or natural abundance. Spectral acquisition parameters have been optimized in order to obtain minimum intensity distortions over the spectral width and in relation to the major sources of inaccuracy: the relaxation times, the decoupling pulse and power, and nuclear Overhauser effects. A major reduction in experimental time resulting from a study of the relaxation times and variance analysis has been achieved. The influence of (1)H decoupling conditions on peak areas was shown to be critical in that different relative peak areas are obtained according to the decoupling power. The efficiency with which the quantitative (13)C NMR method can determine site-specific (13)C/(12)C ratios in natural products has been tested for 12 independent samples of vanillin from different sources. Discriminatory analysis performed in the space defined by the site-specific carbon isotope ratios allows natural vanillin and that from different synthetic origins to be unambiguously distinguished.
authors.affiliation: 1- LAIEM -CNRS UMR 6006, Faculté des Sciences et Techniques, Université de Nantes, 2 rue de la Houssinière BP 92208, 44322 Nantes cedex 3, France. eve.tenailleau@chimbio.univ-nantes.fr
authors.forename: Eve
authors.initials: E
authors.lastname: Tenailleau
authors.forename: Pierre
authors.initials: P
authors.lastname: Lancelin
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Robins
authors.forename: Serge
authors.initials: S
authors.lastname: Akoka
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry*; D001688:Biological Products / Q000737:chemistry*; D002247:Carbon Isotopes / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012680:Sensitivity and Specificity; D013499:Surface Properties
chemical_list: D001547:Benzaldehydes; D001688:Biological Products; D002247:Carbon Isotopes; C100058:vanillin