The headspace compositions of 13 pepper and peppercorn samples of different species, colloquially also referred to as pepper, were analyzed, and more than 300 compounds were tentatively characterized by means of comprehensive two-dimensional gas chromatography in tandem with flame ionization detection, quadrupole mass spectrometric detection and time-of-flight mass spectrometric detection (GC x GC-FID, GC x GC/qMS and GC x GC/TOFMS, respectively). The analysis of volatile organic compounds (VOCs) was performed after solid-phase microextraction (SPME) using a 75-microm PDMS/DVB fibre. Fingerprint comparison between the three techniques permitted peaks to be assigned in the GC x GC-FID experiment based on the analogous MS analysis, taking into account retention shifts arising from method variations. When using GC x GC/TOFMS, about five times more peaks were identified than in GC x GC/qMS. Retention indices for all peaks were calculated in the bi-dimensional column set comprising of a 5% phenyl polysilphenylene-siloxane primary column and a polyethylene glycol second column. The spectra obtained by both mass detection techniques (qMS and TOFMS) give very similar results when spectral library searching was performed. The majority of the identified compounds eluted as pure components as a result of high-resolution GC x GC separations, which significantly reduces co-elution, and therefore increases the likelihood that pure spectra can be obtained. The differences between TOFMS and qMS (in fast scanning mode) spectra were generally small. Whilst spectral quality and relative ion ratios across a narrow peak (e.g. w(b) approximately 100-150 ms) do vary more for the fast peaks obtained in GC x GC/qMS operation, than with TOFMS, in general adequate spectral matching with the library can be achieved.

SummaryThe composition of the volatile terpenes emitted by different trees has been successfully used as markers in a wide variety of studies such as chemotaxonomy. In this work discrimination among ten pine species, R pinea, R pinaster, R brutia, R elliottii, R halepensis, R kesiya, R radiata, R patula, R sylvestris, and R taeda was achieved by analyzing the relative composition of their volatile emissions. The analysis was performed after simultaneous distillation extraction; 16 monoterpenes were identified. My means of principal component analysis it was shown that discrimination among species could be maximized by taking into account three monoterpenes only -~z-pinene,/~-pinene, and hmonene. In a second stage of the work the extracts were submitted to enantiomer-selective multidimensional gas chromatography (MDGC). The enantiomer ratio was determined after separation on a tailor-made 2, 3-dimethyl-6-9 methylsilyl-/~-cyclodextrin analytical column. Application of principal component analysis to the samples enabled their comparative characterization.

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