**2.4 Gas chromatography coupled with mass spectrometry (GC-MS)**

Gas chromatography-electron impact mass spectrometry (GC-EIMS) analyses were assessed using an Agilent 7890B gas chromatograph (Agilent Technologies Inc., Santa Clara, CA, USA) equipped with an Agilent HP-5MS (Agilent Technologies Inc., Santa Clara, CA, USA) capillary of 12 column (30 m × 0.25 mm; coating thickness 0.25 μm) and an Agilent 5977B single quadruple mass detector (Agilent Technologies Inc., Santa Clara, CA, USA). The conditions of sample analysis were as following: injector and transfer line temperatures 220 and 240°C, respectively; oven temperature programmed from 60 to 240°C at 3°C/min; carrier gas helium at 1 mL/min; split ratio 1:25. The acquisition parameters were as follows: full scan; scan range: 30–300 m/z; scan time: 1.0 s.
