Thermo trace dsq

  Freeze dryer: Free Zone 12 L vertical freeze dryer, USA, Labconco

  Ultrasonic cracker: SONICS 750, USA, SONICS

  Vortex mixer: XW-80A, China, Shanghai Medical University Instrument Factory

  High speed refrigerated centrifuge: Avanti J-30, USA, Beckman Kurt, Hongkong

  Gas chromatography-quadrupole mass spectrometer: Thermo Trace DSQ, USA, Thermo

  Column: TR-5ms, 60 m ∗ 0.25 mm ∗ 0.25 m, USA, Thermo

the specifications of the chromatographic column were 60 m × 0.25 mmi.d.×0.25 μm, TR-5MS

the initial temperature was set to 80°C and kept for 2 minutes before being ramped up to 140°C at a rate of 10°C/min. The temperature then continued to be ramped up to 240°C at a rate of 4°C/min and to 280°C at a rate of 10°C/min, then held at 280°C for 10 minutes

the carrier gas was helium with a flow rate of 1.0 mL/min

the temperature of the injection port was 280°C, and the injection volume was 0.2 μL

the solvent delay was 8 minutes

the temperature of the ion source was 250°C, and the temperature of ports was 280°C

MS scanning range was from 40 to 500 Da by M/Z

the ionization mode was EI

the electron energy was 70 eV