A bench top Varian gas chromatograph (Model 450-GC) connected
to a Varian mass spectrometer (Model 320-MS TQ)
equipped with a Varian autosampler (Model CP 8400) was used
in this study. Separations were performed on a Varian Inc Factor
Four VF-5 ms (30 m long 0.25 mm i.d. 0.25 lm film thickness)
capillary column with helium gas at constant flow rate
of 1.2 mL min1 (linear velocity 40.3 cm s1), using splitless
mode of injection. The autosampler injected 1 lL volume of sample
extract or standard solutions into the GC system with gradient
oven temperature starting from 50 C for 1 min, to 150 C at
10 C min1, to 250 C at 8C min1, and to 300 C at
10 C min1, and held at final temperature for 6 min with a total
run time of 34.50 min. The mass spectrometer scan time was
25.0 min. The injector and transfer line temperature were
240 C and 275 C, respectively. The ion source temperature
was 240 C and operated in positive electron ionization (EI)
70 eV mode.