2.4. GC-FID and GC-MS Analysis of FAMEs

FAMEs were quantitatively analyzed with GC (Agilent 7890B, Agilent Technologies Canada, Inc., Mississauga, ON, Canada) equipped with an autoinjector, an FID, and an SP-2560 capillary column (100 m, 0.20 μm film thickness, 0.25 mm ID; Merck KGaA, Darmstadt, Germany). The injector and the detectors were maintained at 250 °C and 260 °C, respectively. The inlet flow was 2 mL/min with a constant pressure of 54 psi. The FID parameters of hydrogen (H₂) fuel flow, airflow, and make flow (nitrogen, N₂) were set to 30, 400, and 25 mL/min, respectively. The column oven temperature was kept at 140 °C for 5 min, then progressively increased to 240 °C for 25 min (linear temperature program 4 °C/min and held at 240 °C for 15 min [15]. The FAMEs were precisely identified by comparing them with the retention time with authentic standards. For a more accurate qualitative analysis, the mass spectra were also recorded using a GC-MS system (QP2010 SE; Shimadzu, Kyoto, Japan), following the optimized GC-FID analysis thermal program. The identity of FAMEs was confirmed by comparing their fragmentation pattern with authentic standards, and also by using the National Institute of Standards and Technology (NIST; U.S. Department of Commerce, Gaithersburg, MD, USA) mass spectrum database (NIST08 and NIST08s).