Helium was
used as carrier gas at a flow rate of 1.0 mL/min. The temperature
program of the oven was the same as that of GC–FID analysis
mentionedabove.The ionsource temperatureofMSwasmaintained
at 250 8C, with an ionizing energy at 70 eV. A scan range of 50–
500 m/z was used for full scan analysis of samples.