Thermo fisher mass spectrometer

GC–MS analysis was performed by a Thermo Fisher Trace 1310 gas chromatograph (Thermo Fisher Scientific, Waltham, MA, USA) coupled with a Thermo Fisher mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). A TG-WAX column (30 m × 0.25 mm i.d., 0.25 μm, Thermo Fisher Scientific, Waltham, MA, USA) was used for separation, and helium was used as the carrier gas. The separation was carried to the chromatographic column at a fixed flow rate of 1.0 mL/min. The initial temperature was 40 °C for 1 min, which was then increased to 140 °C at a rate of 2 °C/min, followed by a 1 min hold. Finally, it was increased to 220 °C at a rate of 6 °C/min and held for 1 min. Mass detector conditions were as follows: ionization energy, 70 eV; transmission line temperature, 250 °C; ion source temperature, 250 °C; mass range, m/z 45–350; and solvent delay, 5 min.

GC–MS was performed using a Thermo Fisher Trace 1310 gas chromatograph (Thermo Fisher Scientific, Waltham, MA, USA) coupled with a Thermo Fisher mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). Isolates were analyzed using TG-Wax MS columns (30 m × 0.25 mm i.d., 0.25 μm, Thermo Fisher Scientific, Waltham, MA, USA). The carrier gas was high-purity helium (99.999%) at a fixed flow rate of 1.0 mL/min into the column. The initial oven temperature was 40 °C for 1 min, which was then increased to 130 °C at a rate of 2 °C/min and held for 1 min, and finally, increased to 220 °C at a rate of 10 °C/min and held for 8 min. The sample was injected in 1 μL at 250 °C in a 1:30 split ratio.The mass detector conditions were as follows: ionization energy, 70 eV; ion source temperature, 250 °C; mass range, m/z 45–500; solvent delay, 5 min.
Volatile flavor compounds were identified by comparing their retention indices and mass spectra with those of reference standards in the NIST 14 mass spectra database. Retention indices were calculated for each volatile compound using the retention times of a homologous series of n-alkanes (C₁₀–C₂₈).