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Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C(6) aldehydes and alcohols), which contribute significantly to the "green" flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of polymeric coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate technique for routine quality control due to its operational simplicity, repeatability, and low cost.

A commercial sample of the essential oil of Chenopodium ambrosioides L. from Madagascar was analysed by GC, GC-MS and 13C-NMR. By GC analysis, the major constituents were found to be ascaridole (1) (41.8%), isoascaridole (2) (18.1%), p-cymene (16.2%), alpha-terpinene (9.7%) and limonene (3.8%). However, ascaridole undergoes a partial thermal isomerisation to 2 and hence the amount of 1 is under-estimated by GC analysis. The actual contents of 1 and 2 (55.3 and 4.6%, respectively) were obtained following combined analysis of the sample by GC and 13C-NMR. Several hydroxy- and polyhydroxy-menthanes were identified by 13C-NMR.

The essential oils of six Helichrysum species from Madagascar were investigated and 46 components were identified by GC, GC-MS and 13 C-NMR spectrometry. The main constituents were 1,8-cineole for H. gymnocephalum (59.7%) and H. bracteiferum (27.3%);ˇ-pinene for H. selaginifolium (38.2%); (E)-caryophyllene for H. cordifolium (55.6%), H. faradifani (34.6%) and H. hypnoides (34.0%).

A commercial sample of Cedrelopsis grevei H. Baillon from Madagascar was repeatedly chromatographed and the combined analysis of all the fractions by GC, GC-MS and 13 C-NMR led to the identification of 114 components. The major constituents were (E)-β-caryophyllene (9.3%), α-copaene (7.7%), α-selinene (5.8%), δ-cadinene (4.9%), β-selinene (4.5%), α-humulene (3.3%) and β-bisabolene (2.8%). Analysis of five other commercial samples confirmed the pre-eminence of sesquiterpene hydrocarbons and exhibited a variation in the contents of the main components: ishwarane (1.0-17.4%), (E)-β-caryophyllene (1.3-12.5%), α-copaene (4.9-11.0%), β-elemene (0.2-9.6%) and α-selinene (1.1-9.4%).

Headspace solid-phase microextraction (HS-SPME) -gas chromatography using flame ionization detection and multivariate analysis were applied to the study of the specificity of protected designation of origin (PDO) virgin olive oils produced in a southern French region (Alpes-Maritimes) based on their volatile compounds. A total of 35 PDO olive oils from Nice, 6 commercial oils, and 12 other French PDO olive oils were analyzed. Recorded data were subjected to principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The method developed here was able to perfectly distinguish different qualities of olive oils. Representative samples from each class obtained by chemometric treatment were analyzed by HS-SPME and GC-MS. PCA and SIMCA of chromatographic data were related to sensory analysis and led to a better understanding of the chemical features and observed sensory effects of olive oils.

4-Epi-cis-dihydroagarofuran was isolated from the bark oil of Cedrelopsis grevei and its structure was elucidated by 1D and 2D-NMR spectroscopy.

The combined analysis of a commercial sample of Helichrysum faradifani Sc. Ell. essential oil from Madagascar, using column chromatography, GC-RI, GC-MS and 13