2.3. Compound identification
Composition of the essential oils were determined by GC and
GC-MS. GC analysis was done on an Agilent Technologies 7890 GC
equipped with FID and a HP-5MS 5% capillary column
(30.00m 0.25 mm, 0.25 mmfilm thicknesses). The carrier gas was
helium at a flow of 0.8 mL/min. Initial column temperature was
60 C and programmed to increase at 4 C/min to 280 C. The split
ratio was 40:1. The injector temperature was set at 300 C. The
purity of helium gas was 99.999% and 0.1 mL samples were injected
manually in the split mode.
GC-MS analysis was done on the mentioned Agilent Technologies
5975 Mass system. Mass spectra were recorded at 70eV. Mass
range was from m/z 50 to 550.
Constituents were identified by comparison of their RI (retention
index) relative to C5eC24 n-alkanes obtained on a nonpolar HP-
5MS column by comparison of the RI, provided in the literature, by
comparison of the mass spectra with those recorded by the NIST 08
(National Institute of Standards and Technology) and Willey
(ChemStation data system). The individual constituents were
identified by retention indices and compared with constituents
known from the literature (Adams, 2007; McLafferty, 2009). The
percentage composition was computed from the GC peak areas
without using any correction factors.