6850 series 2

Fatty acid methyl esters (FAMEs) concentrations were measured following transesterification using gas chromatography. The profile of fatty acids was assessed with a gas chromatograph equipped with an FID detector (Agilent Technologies 6850 Series II, Santa Clara, CA, USA) post-transesterification. The GC method of [53 ], with modification, was used. Briefly, 1 μL of the solution containing the FAMEs was injected into gas chromatograph equipped with a capillary column (100 m × 0.25 mm inner diameter, film thickness of 0.20 μm) with a polystationary phase (90% biscyanopropyl/10% cyanopropylphenyl siloxane) (Supelco, Bellafonte, PA, USA), hydrogen flame ionization detector (FID), and a programmed temperature vaporizer (PTV). Helium with a flow rate of 1 mL min⁻¹ was used as gas carrier. The oven temperature program was as follows: 140 °C × 5 min, a 4 °C min⁻¹ ramp to 175 °C for 20 min, and a 3 °C min⁻¹ ramp to 240 °C for 20 min. The chromatogram peaks were identified using an external 37-component standard (Supelco, Bellefonte, PA, USA). The results are expressed as relative % values.

Sugar consumption and fermentation end-products were measured as previously reported52 (link) using a Waters Breeze 2 high-performance liquid chromatography (HPLC) system (Waters Corp., Milford, MA) equipped with an Aminex HPX-87H column (Bio-Rad Laboratories, Hercules, CA) and a refractive index detector. Headspace hydrogen was measured using an Agilent Technologies 6850 Series II gas chromatograph equipped with a Carboxen 1010 plot column and a thermal conductivity detector. Total H₂ production calculations (headspace and liquid fractions) were done as previously described53 (link).

Regarding plasma fatty acid profile, the analysis was carried out blind to the subject status. Plasma was stored at −80 °C until used for analysis. Lipids were extracted with different chloroform/methanol mixtures according to Folch [33 (link)] and fractionated by HPLC-ELSD and analyzed as previously describe [34 (link), 35 (link)].
Fatty acid composition of whole plasma was determined by gas-chromatographic analysis. The fatty acid methylesters, obtained after trans-derivatization with sodium methoxide in methanol 3.33 % w/v, were injected into gas chromatograph (Agilent Technologies 6850 Series II) equipped with a flame ionization detector (FID) under the following experimental conditions: capillary column: AT Silar length 30 m, film thickness 0.25 μm, Gas carrier: helium, temperature: injector 250 °C, detector 275 °C, oven 50 °C for 2 min, rate of 10 °C min-1 until 200 °C for 20 min. A standard mixture containing methyl ester fatty acids was injected for calibration.