2.6.2. GC-MS Analysis

Gas chromatography-mass spectrometry (GC-MS) analysis was carried out using Varian Saturn 2000 (Les Ulis, France) ion trap GC/MS and CP-3800 GC system equipped with fused silica capillary DB-5MS column (5% phenylmethyl Polyoxane, 30 × 0.25 mm, film Thickness 0.25 μm) [25]. Chromatographic conditions were 60–260°C, and the temperature was increased in a gradient of 5°C/min and continued for 15 minutes under isothermal conditions of 260°C. Apply a second gradient to reach 340°C at a rate of 40°C/min. The temperature of the trap was 250°C and the temperature of the transmission line was 270°C. Perform quality scans from 40 to 650 m/z. The extract was dissolved in its extraction solvent in an amount of 5 mg/mL, and 2 μL was injected. The molecules were identified by comparing the retention index (RI) obtained on a nonpolar DB-5MS column versus C5–C24 n-alkanes with compounds provided in the literature and comparing their mass spectra with the NIST 08 (National Institute of Standards and Technology) database.

(1) Derivatization Method. Rahmani et al. [25] described the derivatization method and made some modifications. In a 2 mL vial, mix 150 μL of 99% N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) + 1% of chlorotrimethylsilane (TMCS) with 1 mL of extract (5 mg/mL in tetrahydrofuran (THF) solvent). After that, the blend was mixed for 30 seconds to increase solubility. The reaction mixture was kept at 40°C for 15 minutes. Then, ten microliters (10 μL) of each derivative solution was injected into the same GC-MS equipment and analyzed as described in the previous section to identify the molecules of each extract.