Chromquest 5.0 software package

Gas chromatography with flame ionization detector (GC-FID) (Thermoquest Trace GC 2000, Austin, TX, USA) and DB5-MS capillary column (25 m × 0.25 mm, 0.25 μm film thickness, Agilent Technologies, Santa Clara, CA, USA) was used to analyze the chemical composition of TTO. The oven temperature was as follows: 45 °C for 1 min, 45 °C to 94 °C with 4 °C/min rise and increased to 180 °C at a rate of 2 °C/min then followed by an increase from 20 °C/min to 240 °C. Helium was the carrier gas, and the flow rate was 1.3 mL/min, splitless, injection temperature was 225 °C and FID temperature was 250 °C. TTO was diluted in 1 in a 1000 ratio for analysis by GC-FID and gas chromatography–mass spectrometry (GC–MS). Hexadecane was added to the oil as an internal standard to make a final solution equivalent to 5g per μL. The ChromQuest 5.0 Software Package (Thermo Fisher Scientific Inc. Waltham, MA, USA) was used for chromatogram analysis. The experiment was performed in triplicate.

Enantiomeric separation of terpinen-4-ol and α-terpineol was achieved with an Rt-βDEXse column (30 m, 0.32 mm × 0.25 μm column, Restek Corporation, Bellefonte, PA, USA) using a Trace GC Ultra (Thermo Scientific, Waltham, MA USA). Helium was used as a carrier gas at 1.2 mL/min. The samples were analyzed with a split ratio of 10:1. The injector and FID temperatures were 225 and 230 °C, respectively. Column temperature for terpinen-4-ol: 50–80 °C at 3 °C/min, 80−105 °C at 10 °C/min, 105−120 °C at 3 °C/min, 120−180 °C at 10 C/min and hold for 10 min; for α-terpineol: 70 °C for 3 min, 3 °C/min to 120 °C, 5 °C/min to 220 °C and hold for 10 min. The ChromQuest 5.0 Software Package (Thermo Fisher Scientific Inc. Waltham, MA, USA) was used for analysis in comparison with authentic samples. All analyses were made in triplicate.