Qualitative and quantitative analysis by GC–MS
The final samples were analysed on an Agilent 7890A GC,
equipped with an Agilent 7683 autoinjector, coupled to an Agilent
5975C mass-selective detector. MS with electron-impact (EI) ionisation
(electron energy, 70 eV) was performed in the selected ion
monitoring (SIM) mode. The column temperature program was
as below: 60 C hold for 0 min, ramp at 30 C min1 to 100 C, hold
for 3 min, ramp at 3 C min1 to 220 C, hold for 3 min, ramp at
10 C min1 to 280 C, and hold for 10 min. The carrier gas (helium)
flow rate was 1.2 mL min1, injection port temperature was 250 C,