DB-5 capillary column
(30 m × 0.25 mm, 0.25 μm film thickness) (Agilent Technologies) and
desorbed at 250 °C for 3 min. The injection port was operated in split
mode (1:10), and 99.999% pure heliumwas used for vial pressurization
and as the carrier gas. The helium flow rate was 1.4 mL/min. The initial
oven temperature was 40 °C (2 min),whichwas ramped up at 5 °C/min
to 170 °C and held there for 2 min. Then it was ramped up at 10 °C/min
to 250 °C and held there for 5 min. The mass detector was operated in
the electronic impact (EI) mode at 70 eV and the source temperature
was set at 250 °C. The mass spectra were scanned in the m/z
29–350 amu range at 1 s intervals.