AUTHENTICATION OF ESSENTIAL OILS CONTAINING LINALOOL AND LINALYL ACETATE BY ISOTOPIC METHODS

Site-specific natural isotope fractionation studied by NMR (SNIF NMR) combined with molecular isotope ratio determination by mass spectrometry (IRMS) was used to characterize linalool and linalyl acetate obtained from chemical synthesis or extracted from essential oils of well-defined botanical and geographical origins. In general, the overall carbon-13 or deuterium contents measured by IRMS do not constitute efficient criteria for identifying natural and synthetic samples. In contrast, the non-random distribution of deuterium exhibits large variations as a function of the origin of the sample. A discriminant analysis performed in a space defined by the 10 site-specific hydrogen isotope ratios and the overall carbon isotopic parameter enables the natural and synthetic species to be unambiguously distinguished. In spite of the relatively large dispersion of the isotope ratios exhibited by both natural and synthetic families, it is possible to develop an efficient strategy to carry out qualitative and quantitative analyses of the essential oils.