The volatile constituents were analyzed with an Agilent 5975C mass selective detector coupled to an Agilent 7890A gas chromatograph, equipped with a DB-5 capillary column (30 m × 0.25 mm, 0.25 μm film thickness, Agilent Technologies). Helium (flow rate, 1.2 mL/min) was used as the carrier gas. The injector temperature was 250 °C. The oven temperature program was 40 °C for 2 min, increased by 5 °C/min to 150 °C and was maintained for 1 min, then increased by 10 °C/min to 250 °C and held for 5 min. Mass spectra were recorded at 70 eV in electron impact (EI) ionization mode. The temperature of the quadrupole mass detector and ion source were 150 and 230 °C, respectively. The temperature of transfer line was 280 °C. Mass spectra were scanned in the m/z range of 29–300 amu with 4.37 scan/s and no solvent delay. The mixture of n-alkanes (C5–C8, C8–C20, 40 mg/L each component in hexane, purchased from Sigma–Aldrich, Germany) run under the same conditions as the samples to calculate the Retention Index (RI) of volatile compounds. Tentative identification of the volatile components was done by comparing the mass spectra of the samples with the data system library (NIST 11), retention index (RI) and authentic references.