GC/FID analyses were performed using an Agilent 7890A GC System equipped with an FID detector (Agilent Technologies).
The separation was conducted on a HP-5MS column 30 m 0.25 mm with 0.25 m m film thickness. Helium was used as carrier
gas with an initial flow rate of 0.6 ml/min and subsequently at a constant pressure of 50.0 psi. The front inlet was maintained
at 250
C in a split ratio of 50:1. The GC oven temperature increased from 60
C to 260
C at a rate of 5
C/min, and the FID
operated at 250
C with an air flow of 350 ml/min and a hydrogen flow of 35 ml/min. The injection volume was 1.0 m L.
GC/MS analyses were performed using an Agilent 7890A GC system coupled to a 5975C MSD (Agilent Technologies). The
ionisation energy was 70 eV with a mass range of 40e400 m/z. The separation was conducted with the same column and
temperature program as for the analytical GC.
Identification of the each components of the essential oil was made by comparing their Kovats retention indexes with
those in literature (Adams, 2009). The calculation of the Kovats index was made based on a linear interpolation of the
retention time of the homologous series of n-alkanes (C9eC20) under the same operating conditions. The components were
also identified by comparing the mass spectra of each constituent with those stored in the Wiley/NIST 05.L database and with
mass spectra from the literature (Adams, 2009).