Isq qd mass selective detector

For transesterification, samples were mixed with 200 µL methanolic sodium hydroxide (0.5 mol/L; Sigma-Aldrich, St. Louis, MO, USA) and incubated at 60 °C for 45 min while shaking. Next, 300 µL methanolic boron trifluoride solution (1.3 mol/L; Sigma-Aldrich, St. Louis, MO, USA) was added, and incubation was continued for another 30 min. The reaction was stopped by the addition of 200 µL saturated sodium chloride solution. FAMEs were extracted with n-hexane and subjected to GC-MS analysis. Capillary GC-MS analysis was performed using a Trace 1300 GC with an ISQ QD mass selective detector and a PTV injector (Thermo Fisher Scientific, Waltham, MA, USA). One microliter of sample was separated using a DB-23 column (60 m × 0.25 mm, film thickness: 0.25 µm; Agilent, Santa Clara, CA, USA) and a constant helium carrier gas flow of 1.5 mL/min. The injector temperature was set to 240 °C. The oven temperature program was as follows: 130 °C for 5 min; heating to 170 °C at 6.5 °C/min; heating to 215 °C at 1.50 °C/min; 215 °C for 12 min; heating to 240 °C at 5.0 °C/min; and 240 °C for 10 min. The mass spectra were recorded over 40–500 m/z. Quantification was carried out using external calibration with specific FAME standards in the range of 5–400 µg/mL. The amount of individual fatty acids was determined relative to the total fatty acid content.