Scion 456 gc

We prepared the fatty acids methyl ester (FAME) of soybean oil as described by Meng et al. [8 (link)]. The oil sample (1 g) was mixed with 12 mL of 2% NaOH-methanol solution, heated at 80 °C, and shaken until the oil completely disappeared. Then, 14 mL of boron trifluoride BF₃ (15%) was added after cooling the mixture, followed by 30 mL of n-hexane and 100 mL of saturated NaCl. The samples were shaken for 10 min before adding 10 g of anhydrous Na₂SO₄ to remove the water. The fatty acid composition from the supernatant was analyzed using gas chromatography (Scion 456-GC, Goes, Stanleyweg 4, The Netherland).
FAME (1 µL) was injected into the gas chromatography equipped with FID (Flame Ionization Detector) and capillary Rt-2560 column (100 m long × 0.25 mm I.D. × 0.25 µm film thickness). The oven temperature was increased from 170 °C to 220 °C with increments of 4 °C/min and then to 250 °C at 1 °C/min. The injector and the detector were at 220 °C and 250 °C, respectively. Helium was used as the carrier gas at a flow rate of 1 mL/min. The formed methyl esters were identified by comparing their retention time to standard methyl esters of fatty acids.

Butyrate measurements were performed either in culture supernatants or in the in vitro gut model as described above. In the case of the in vitro gut model, butyrate was not measured in non-irradiated samples due to the presence of other microorganisms potentially also producing butyrate. To quantify the butyrate production in the in vitro gut model, the spiked faecal samples were homogenised and stored at −20 °C until processed and prior to measurement were diluted (1:4) in sterile water and homogenised in a stomacher (Seward, Premier, Scientific, Portsmouth, UK). Butyrate was also measured (0, 3, 6, 12, 24 h) in supernatants of the control sample (no Aq) and in the in vitro experimental growth cultures containing 0.2%, 0.5%, 1% and 2% Aq. All experiments and measurements were performed in triplicates. Butyrate production was measured by GC-MS (SCION-456-GC) as previously described [28 (link)].

Produced biodiesel was analysed on a Bruker GC-MS (Bruker SCION 456/GC, SCION TQ MS) equipped with a ZB-5MS (30 m × 0.25 mm internal diameter, 0.25 μm film thickness, Phenomenex) capillary column using helium as carrier gas. The temperature program was 60 °C (1 min), 30 °C min⁻¹ to 120 °C, 5 °C min⁻¹ to 250 °C, and 20 °C min⁻¹ to 300 °C (2 min). Injection temperature was 300 °C. For identification and quantification of the FAME total ion mode was used. Because of differences in the response factors, for each FAME separate calibration curves were determined in triplicate, using the Supelco^® 37 Component FAME Mix (Sigma-Aldrich, Sintra, Portugal) commercial standard. In the case where no standard was available, the response factor of the most similar FAME, in terms of structure, was used. Results are expressed as a percentage of total FAME content.