Db wax elastic quartz capillary column

Instruments used in this study included: a DF-101S heat-collecting magnetic stirrer (Zhengzhou Yarong Instrument Co., Ltd., Zhengzhou, China), a solid-phase microextraction (SPME) syringe, a 75 μm carboxen-polydimethylsiloxane (CAR/PDMS) SPME extraction head (Supelco, Inc., Bellefonte, PA, USA), a DB-WAX elastic quartz capillary column (20 m, 0.18 mm, 0.18 μm, Agilent, Santa Clara, CA, USA), and a gas chromatography-mass spectrometer for GC-MS (Thermo Fisher Scientific, Waltham, MA, USA).

Anhydrous sodium sulfate (Na₂SO₄) was purchased from Sinopharm Group Chemical Reagent Co., Ltd. (Shanghai, China); ultrapure water was prepared by Milli-Q (Burlington, MA, USA); difurfuryl sulfide was purchased from TCI (Shanghai) Development Co., Ltd. (Shanghai, China), as the internal standard for quantitative analysis.
An Agilent 7890B gas chromatograph coupled with an Agilent 7000D quadrupole mass spectrometric detector (Agilent, Santa Clara, CA, USA) and standard mass spectrometry library (NIST 2014) workstation was used for the separation and identification of the volatile compounds. A DB-WAX elastic quartz capillary column (30 m × 0.25 mm, 0.25 μm) was used as the stationary phase (Agilent, Santa Clara, CA, USA). Six types of SPME fibers, a manual SPME fiber holder, and n-alkanes (C7–C40) were purchased from Sigma-Aldrich (St. Louis, MO, USA). The 15 mL screw cap headspace vial fitted with PTFE/silicone septa and a magnetic stirring rotor was purchased from ANPEL Laboratory Technologies (Shanghai) Inc. (Shanghai, China).