Model 7890 gas chromatograph

Gas chromatographic analyses were performed with an Agilent gas chromatograph model 7890 equipped using an Agilent 5975 mass spectrometer and 7683 automatic sampler (Agilent, Santa Clara, CA, USA). Samples were separated on an HP-INNOWAX capillary column (60 m × 0.25 mm × 0.25 μm, J &W Scientific, Folsom, CA, USA). The carrier gas was helium (purity > 99.999%) at 1 mL/min. The temperature in the injection port was 250 °C. Samples were injected by placing the SPME fiber at the GC inlet for 8 min in the splitless mode. The oven temperature program was as follows: 50 °C for 1 min, then increased to 220 °C at a rate of 3 °C/min and held at 220 °C for 5 min. The mass detector conditions were as follows: electron impact mode (MS/EI) at 70 eV, mass scanning range m/z 20 to 350 U, ionic source temperature 230 °C. The mass spectrometry interface temperature was 280 °C. The mass spectrophotometer was operated in the selective ion mode under autotune conditions, and the area of each peak was determined using the ChemStation software F.01.01.2317 (Agilent Technologies, Inc. Santa Clara, CA, USA) [44 (link)].

Qualitative analysis was performed using an Agilent gas chromatograph model 7,890 coupled to a Agilent mass spectrometer model 5975 equipped with a DB5 MS column (20 m × 0.18 mm; 0.18 μm). The oven temperature was 50°C and remained constant for 3.2 min; then, it was increased to 300°C at a rate of 8°C/min. The injector temperature was 280°C. Ionization was obtained by electron impact at 70 eV, and the electron multiplier was maintained at 2200 eV. The temperature of the ion source was 230°C. Mass spectral data were acquired in the scan mode in the range m/z 33–450. The flow of carrier gas (helium) was set at 0.9 ml/min; compound identification was made by comparison of their spectra and RI with those of libraries such as Adams (2008), Nist (2008), and Köning, Hochmuth, and Joulain (2001) and were incorporated in the laboratory.

For fatty acids analysis, 0.75 mL of the obtained lipid extract, prepared according to the steps described above, was transferred to a screw-capped glass test tube, and then 0.1 mL toluene and 0.15 mL HCl solution (8.0%) were added. The tube was vortexed and incubated overnight at 45 °C. After cooling to room temperature, 0.5 mL hexane and 0.5 mL water (deionized) were added to the extract of fatty acid methyl esters (FAMEs). The tube was vortexed, and then 0.2 mL of the hexane layer was moved to the chromatographic vial, and 1.6 µL of the extracted samples was analyzed.
The FAME analysis was carried out with an Agilent Model 7890 gas chromatograph equipped with a 5975C mass detector. A capillary column HP 5 MS methyl polysiloxane (30 m × 0.25 mm i.d. × 0.25 mm ft) was used with helium as a carrier gas. The temperature of the column was maintained at 60 °C for 3 min and was increased to 212 °C at a rate of 6 °C min⁻¹, then to 245 °C at a rate of 2 °C min⁻¹, and finally to 280 °C at a rate of 20 °C min⁻¹, at which it was held for 10 min. Split injection of the injection port was performed at 250 °C. Fungal fatty acids were identified through comparison with authenticated reference standards from Sigma–Aldrich (Supelco, Bellefonte, PA, USA), and the results were expressed as a percentage of the total amount of fatty acids.