μm capillary column

The volatiles of each sample were extracted with 75 μm carboxen/poly-dimethylsiloxane SPME-fibre (50 °C, 5 min) and identified through comparison of data obtained from GC–MS (Agilent GC–MS 7890 and DB-WAX 30 m × 0.25 mm × 0.25 μm capillary column, Agilent) and NIST 08 (Gaithersburg, MD, USA). Analyzing Kovats indices (KIs) relative to C₇-C₃₀n-alkanes on the capillary column. Two micro liters of 1,2-dichlorobenzene (50 μg, in 1 mL of methanol) was added to each sample as an internal control. All compounds were analyzed with the available standard compounds for identification. Chromatographic conditions were used as per the methods given by Cai, Zhu, Ma, Thakur, and Wei (2020) . The column flow rate was set as 1.0 mL/min, using helium as a carrier gas. The column temperature program was maintained at 40 °C for 2 min, 40–80 °C at 3 °C/min, 80–120 °C at 4 °C/min, and 120–230 °C at 10 °C/min for DB-WAX column. The GC was equipped with a mass spectrometric detector which was set at a scanning range of 35 to 450 m/z. $\text{Cv}=\frac{\text{Sv}}{\text{Si}}\times \text{Ci}$ where Cv and Ci represent the concentration of volatile compound and internal standard, respectively; Sv and Si corresponded to the peak area of volatile compound and internal standard.