Gc 2010 plus gc system

Five mL of crude enzyme was added to 5 g of colza oil or waste soybean oil, while 0.2 g of methanol (methanol: oil molar ratio of 6:1) was also added to the mixtures. The reaction was performed at 35 °C at 200 rpm for 48 h, and samples were taken at intervals of 24 h. FAME was determined using gas chromatography (GC).
The conversion rates of FAME were determined via GC analysis, which was performed using a Shimadzu GC-2010 Plus GC system (Japan) equipped with a flame ionisation detector and a capillary column (DB-WAX, 30 m × 0.25 μm × 0.25 μm). The reaction sample was diluted in 5 mL n-hexane (containing 0.2 mg n-hexadecane) as an internal standard. The analysed FAMEs included methyl myristate (C14:0), methyl palmitate (C16:0), methyl stearate (C18:0), methyl oleate (C18:1), methyl linoleate (C18:2), methyl linolenate (C18:3), methyl eicosanoate (C20:0), methyl eicosenoate (C20:1), and methyl behenate (C22:0). Methyl heptadecanoate (C17:0) was used as the internal standard. The output of the FAME was then calculated according to Eq. 1 [44 ]: $$\text{Yield}=\frac{\sum \text{Ci}\times V}{m}\times 100\%,$$ where m is the mass of the FAMEs, Ci is the concentration of the FAMEs in the sample, and V is the volume of the sample.

For peak separation and detection, a GC 2010 gas chromatograph equipped with a HP-5 fused silica capillary column (30 m × 0.25 mm × i.d. × 0.25 μm) connected to a triple quadrupole mass spectrometer (SHIMADZU GC-2010 Plus GC system and SHIMADZU TQ8040 mass spectrometer) was used. The chromatographic conditions were as follows: the injection port was heated at 250 °C. Helium was used as a carrier gas, and the flow rate was 1 mL/min. The GC temperature program was set at 50 °C for 2 min, after which it was programed to increase from 40 to 150 °C by 4 °C/min, maintained at 150 °C for 1 min, increased from 160 to 250 °C by 5 °C/min, and finally maintained at 250 °C for 5 min. The following conditions of MS were used: (i) The ion source was electrospray ionization (ESI); (ii) the transfer line and the ion source was heated at 250 °C; (iii) the mass spectrometer was operated in the electron impact of 70e V, scanning the range of 45/500 m/z in full scan acquisition mode, with a scan rate of 0.2 scan/s. The mass spectra and retention time of each GC peak in the total ion chromatography were compared with the data system library (NIST 11 MS Library). The relative abundance of each compound was estimated by relative area (RA). A blank experiment (growth medium not inoculated with ETR-B22) was performed under the same conditions. All measurements were made with three replicates.

The SCFA, including acetic acid, propionic acid, and butyric acid were measured by gas chromatography (GC) [32 (link)]. Samples of the four strains in MRS broth with different carbon sources were collected after 24 h of fermentation and centrifuged at 12,000 rpm for 10 min. The supernatant was collected for GC analysis. To prepare a crotonic acid metaphosphoric acid solution, 0.6464 g of crotonic acid was added into 100 mL of 2.5% (w/v) metaphosphoric acid solution, and 500 μL of supernatant was combined with 100 μL crotonic acid metaphosphoric acid solution and acidified at −20 °C for 24 h. The acidified supernatant was centrifuged at 12,000 rpm for 5 min, and the final supernatant was filtered and used for SCFA concentration detection. Separation was carried out on a GC-2010 plus GC system (Shimadzu Corporation, Kyoto, Japan) with a DB-FFAP column (Agilent Technologies, Inc., Santa Clara, CA, USA) and a hydrogen (H₂) flame ionization detector. The injection volume was 1.0 μL and nitrogen (N₂) was used as the gas carrier at a flow rate of 12.0 mL/min. The flow rates of air, H₂, and N₂ in detector were 400.0, 40.0, and 30.0 mL/min, respectively. The temperature of the injector and detector was kept at 250 °C. The oven temperature program was as follows: initial column temperature of 70 °C, increased to 180 °C at 15 °C/min, and increased to 240 °C at a rate of 40 °C/min.