https://doi.org/10.3390/plants11243535
“The EOs obtained by hydrodistillation were solubilized in dichloromethane (HPLC grade, Tedia, Brazil – Rio de Janeiro) to obtain a final concentration of 1000 ppm. Subsequently, these diluted EOs were submitted to analysis by Gas Chromatography coupled to Mass Spectrometry (GC/MS) in an HP Agilent CG 6890—EM 5973N Equipment – Rio de Janeiro, to identify the constituents by their respective mass spectra. To determine the quantitative parameters of the EOs and calculation of the Retention Index (RI), the analyses were performed by Gas Chromatography Coupled to the Flame Ionization Detector (GC/FID), in an HP-Agilent 6890–Rio de Janeiro equipment. The GC/MS analyses were: HP-5MS capillary analytical column (HP Agilent CG 6890—EM 5973N Equipment–Brazil, Rio de Janeiro (30 m × 0.25 mm i.d. × 0.25 µm film thickness) and temperature ramp from 60 °C to 240 °C, with an increment of 3 °C/min, helium (~99.9999%) as carrier gas, at a constant flow rate of 1.0 mL/min; scanning range of masses (m/z) at 40—600 atomic mass units (u), with impact energy of 70 eV, operating in positive mode. A 1 μL sample of the EOs solution was injected, in splitless flow mode, and with the injector temperature at 270 °C [3,167]. GC/FID analyzes were performed on an HP-5MS capillary analytical column (30 m × 0.25 mm i.d. × 0.25 μm film thickness), with the same temperature program used for GC/MS analyses, but with hydrogen as a carrier gas at a constant flow rate of 1.0 mL/min. The EOs solution by GC/FID was injected under the same conditions as GC/MS. Retention times (Rt) were measured in minutes without correction, and the relative percentage of each compound was determined by the signal area [2,3,55,167,168]. The RIs were calculated from the results of the analysis of a homologous series of saturated aliphatic hydrocarbons (C8-C28, Sigma-Aldrich, Brazil), performed in the same column and conditions used for the analysis by GC/FID. The identification of constituents was made by comparing the mass spectra obtained from data from the equipment’s library (NIST and Wiley https://webbook.nist.gov/chemistry/cas-ser/ (accessed on 1 January 2021)), and records in the literature [169]. All analyses were performed in triplicate and results are presented as average standard deviation (Table S9).”