**2.2 GC-MS analysis**

GC-MS analysis was performed using a Hew Packard 6890 N (Agilent Technologies, Inc., Santa Clara, CA) HS-SPME-GC-MS at chromatographic conditions: injector temperature: 2300°C; injection mode: splitless; carrier gas: helium (2 mL/min); fiber desorption time and reconditioning: 5 min; column: SGE SolGelwax (100 percent polyethylene glycol) 30 m × 0.25 mm; ionization mode: EI (70 eV); scan range: 35–350 amu; ion source temperature: 2000 V with liquid carbon dioxide; MS conditions: ionization mode: EI (70 eV); scan range: 35–350 amu; and ion source temperature: 2000 V.
