title: Deuterium/hydrogen ratio analysis of thymol, carvacrol, gamma-terpinene and p-cymene in thyme, savory and oregano essential oils by gas chromatography-pyrolysis-isotope ratio mass spectrometry.
abstract: Isotope ratio mass spectrometry online coupled with capillary gas chromatography (GC-Py-IRMS) on column INNOWAX is used in the origin specific analysis and the authenticity control of the phenolic essential oils (EOs). Isotopic data delta(2)H(V-SMOW) of thymol and carvacrol in natural essential oils were evidently more depleted than synthetic products (from -49 to 7 per thousand for thymol and -61 per thousand for carvacrol). delta(2)H(V-SMOW) values of p-cymene, gamma-terpinene and thymol in authentic thyme oils (Thymus vulgaris L. and Thymus zygis L.) were found from -300 to -270 per thousand, from -285 to -248 per thousand and from -259 to -234 per thousand, respectively. delta(2)H(V-SMOW) values of carvacrol and p-cymene in authentic oregano oils (Origanum heracleoticum L., Coridothymus capitatus L. and Origanum compactum L.) varied from -223 to -193 per thousand and from -284 to -259 per thousand, respectively. For authentic Satureja montana subsp. montana essential oils, the mean delta(2)H(V-SMOW) value for aromatic compounds were found to be the following: gamma-terpinene -273 per thousand (SD=4.6 per thousand) and p-cymene -283 per thousand (SD=3.0 per thousand), thymol -245 per thousand (SD=1.8 per thousand) and carvacrol -226 per thousand (SD=1.7 per thousand). In addition, p-cymene was previously found as a precursor of the biosynthesis of thymol and carvacrol in thyme oil, thus, we considered p-cymene as an endogenous reference compound (ERC) for D/H ratio analysis. The isotopic fractionation factors alpha(thymol/p-cymene)=1.05 and alpha(carvacrol/p-cymene)=1.08 were obtained and also used to control the authenticity of the phenolic EOs.
authors.affiliation: Service Central d'Analyse du CNRS, USR 59, Echangeur de Solaize, BP. 22, 69390 Vernaison, France.
authors.forename: Tran-Thi
authors.initials: TT
authors.lastname: Nhu-Trang
authors.forename: Hervé
authors.initials: H
authors.lastname: Casabianca
authors.forename: Marie-Florence
authors.initials: MF
authors.lastname: Grenier-Loustalot
mesh_terms: D000081005:Cyclohexane Monoterpenes; D000081007:Cymenes; D003903:Deuterium / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006859:Hydrogen / Q000737:chemistry*; D015394:Molecular Structure; D039821:Monoterpenes / Q000032:analysis / Q000737:chemistry; D009822:Oils, Volatile / Q000032:analysis / Q000737:chemistry*; D015203:Reproducibility of Results; D013943:Thymol / Q000032:analysis / Q000737:chemistry; D046930:Thymus Plant / Q000737:chemistry*
chemical_list: D000081005:Cyclohexane Monoterpenes; D000081007:Cymenes; D039821:Monoterpenes; D009822:Oils, Volatile; D013943:Thymol; C018669:gamma-terpinene; D006859:Hydrogen; C073316:carvacrol; D003903:Deuterium