GC-MS analyses were conducted using an 8890 GC system (Agilent Technologies, Shanghai, China) equipped with a 7650 autosampler (Agilent Technologies, China) and coupled to a 5977C mass spectrometric detector (Agilent Technologies, DE, USA). The GC was configured with an HP-5ms 30 m × 0.25 mm × 0.25 µm film capillary column (Agilent Technologies, USA). A 1 µL sample was injected into the GC with a 50:1 split ratio, and the inlet temperature was set at 250 °C. Helium was used as the carrier gas with a constant flow rate of 1.0 mL/min. The elution gradient was controlled by an oven