The separation and identification of volatile components
was carried out by gas chromatography–mass spectroscopy
(GC–MS). A HP 5890 gas chromatograph coupled with a HP
5971 quadrupole mass selective detector was used for this purpose.
The column was RH-5 ms 30m×0.25mm i.d., 0.25m
film thickness. Helium (purity 4.8) was used as a carrier gas.
Split-less injection was set for 1 min. The oven temperature was
set at 60 ◦C for 10 min and then programmed at 10 ◦C/min to
200 ◦C as the final temperature in 5 min. Detector line temperature
was 280 ◦C. The compounds were identified using Wiley
275 T library. As no internal standard was added, the absolute
peak areas were compared. The relative standard deviation of
the method was around 10%.