Dsq 2

Gas Chromatography-Mass Spectrometry (GC-MS) was performed using a gas chromatograph (Focus GC-Thermo Fisher, Milan, Italy) equipped with a Varian VF-5m (30 m × 0.25 mm × 0.25 μm) capillary column, combined with a single quadrupole mass spectrometer (DSQII-Thermo Scientific, Milan, Italy) [12 (link)]. The samples were diluted 1:1000 in ether. One microliter of the sample was injected in spitless mode at a temperature of 220 °C. The column flow rate was 1 mL min^-1 using helium as carrier gas. The initial GC oven temperature was 55 °C, increased by 4 °C min⁻¹ to 240 °C with a hold time of 3 min. The transfer line temperature was 250 °C. The MS was operated using electron impact (EI) at an ionization energy of 70 eV. The ion source temperature was set at 250 °C. The solvent delay for the mass spectrometry was set at 3 min and the EI scan mode was used for identification, covering the range of 25–350 m/z. The compound was identified by comparison with the NIST database (https://www.nist.gov/pml/atomic-spectra-database, accessed on 6 June 2021). The instrumentation performance, chromatograms, mass spectra, and initial data processing were carried out with the supplied Xcalibur software (Thermo Fisher, Milan, Italy).

Chemical fingerprinting of wild and commercial EOs of G. fragrantissima were carried out by GC-MS using the model DSQ II (Thermo Scientific, USA) with a fused silica capillary column (30 m by 0.32 m i.d., the film thickness of 0.25 µm) and a TR 50 mass spectrometer. To perform GC-MS, an electron ionization system was maintained at 70 eV and the flow rate of the carrier gas (helium) was kept at 1 ml/min. The injector and detector lines were set at 250 °C and 290 °C, respectively. The initial oven temperature of 50 °C was kept for 1 min and subsequently raised to 310 °C gradually increased by 20 °C/min with a holding time at 310 °C for 15 min. A postrun temperature of 70 °C for 10 min was adequate for the subsequent insertion. The diluted samples (1:100 (v/v) were injected manually in split-less mode. The relative percentage of compounds were estimated by normalizing peak areas. Identification of compounds was achieved by matching the experimental mass spectra to the mass spectra available in the NIST library.

Thermo Scientific DSQ™ II gas chromatography coupled with a mass spectrometry detector, was performed with the same conditions that were previously described in Gas Chromatography. MS data were collected and processed on an Xcalibur™ version 1.4.1. For mass spectrometry conditions, the electron ionization was 70 eV.

The n-hexadecane content in each supernatant was extracted using an equal volume (1:1 v/v) of ethyl acetate. Afterwards, 1 mL of the polar phase was analyzed using a Thermo Scientific DSQII single quadrupole gas chromatography mass spectrometry (GC/MS) system with an HP-5MS column (operating at a pulsed split ratio of 1:1 and a split flow rate of 1 mL/min). The oven temperature was first set and maintained at 40°C for 3 min, followed by a gradual temperature increase at a rate of 6°C/min up to 300°C, with a final 2-min hold at that temperature. The quantification of n-hexadecane is achieved by comparing the peak areas of the test sample with those of the standard sample. The amount of n-hexadecane was adjusted by considering its mass spectrometer response factors, which were determined by analyzing dilution series of commercial standards.

Manure volatile analyses were carried out on a gas chromatograph (Focus GC, Thermo, USA) coupled to a single quadrupole mass spectrometer (Thermo DSQ II, USA). The MS parameters used were as follows: electron impact ionization energy 70 eV and an m/z range from 41 to 300, and the spectra were collected at 6 scans/sec. The GC was equipped with a split/splitless injection port with an SPME glass liner (1 mm ID x 120 mm straight long, ThermoFischer, USA) and a DB5 column (30 m × 0.25 mm × 0.25 μm; J&W Scientific, Folsom, CA, USA) with helium carrier gas (1.2 ml min^–1). The injection port was maintained at 250 °C, and the SPME fiber was left extended in a splitless state for 5 min before the injector split was activated. After desorption, the fiber remained in the injector port for another 3 min. The oven temperature was programmed to start at 60 °C for 1 min, increase by 5 °C min^–1 to 250 °C and then hold at this last temperature for 15 min. The transfer line temperature was 280 °C. Xcalibur software (Thermo Fisher) was used for data processing and reporting of GC-MS analyses. Target compounds were identified by comparing their mass spectra with those in the Wiley 275L library and matching their retention times and mass spectra to those of authentic standards.