Analysis by GC and GC-MS
Essential oils analysis
Quantitative and qualitative analyses of the oils were performed by capillary GC and GC/mass spectrometry (GC/MS), respectively. GC analysis of the essential oils was carried out on a chromatograph (Shimadzu GC-17A) equipped with fused silica capillary columns (30 m, 0.25 mm, 0.25 µm) of different polarities, 1 coated with DB-5, and another with Carbowax 20 M. The temperature was programmed from 60 to 300 °C at 3°C/min for DB-5 and 60 to 250 °C at 3 °C/min for Carbowax 20 M. Injector and detector temperatures were set at 220 and 250 °C, respectively. The GC apparatus was equipped with a flame ionization detector, while the GC/MS analysis involved a quadrupole MS system (QP 5000), operating at 70 eV and over a mass range of 40 to 400 a.m.u. The relative composition of the oils was obtained by electronic integration, without taking relative response factors into account. The components of the oils were identified by comparison of retention indixes (determined relative to the retention times of ƞ-alkanes homologous series) and mass spectra with those of authentic samples, data from the Nist GC-MS library and reports in the literature (Adams 2001: Apel and others 2002).