2.4. Gas chromatography–mass spectrometry (GC–MS) analysis
Composition of essential oils was analyzed by using gas chromatography–mass spectrometry (GC–MS; Shimadzu GC–MSQP2010). The system was equipped with AOC-20i/s auto sampler with BPX5 capillary column (length: 30 m; thickness: 0.25 m;diameter: 0.25 mm). Helium was used as a carrier gas (flow rate:1 ml/min;pressure: 53.5 kPa). The injector, operated in splitless mode (1:50), was held at 230 ◦C. The oven temperature programme was started at 50 ◦C and after 2 min, was ramped at 4 ◦C/min up to 220 ◦C, and was finally held at 220 ◦C for 15.5 min (60 min run). pounds (ofthe essential oils) were identified by the NIST MS-Search software through the comparison ofthe obtained mass spectra with the mass spectra in the NIST 2008 database spectral library.