Millipore 0.45 μm pore size filter

To analyze short chain fatty acids (SFCAs) acetate, propionate, butyrate and succinate, and organic acid lactate at the end of the experiment, a volume of 500 µL of fermentation was centrifuged at 14,000 rpm for 60 min, filtered through a Millipore 0.45 μm pore-size filter (Billerica, MA, USA), and diluted ½ in MilliQ quality water. The quantification was conducted on a HPLC Acquity equipped with an Aminex HPX-87H 300 × 7.8 mm column (BioRad) under conditions defined by manufacturer. Detection was achieved by a refractive index detector. The eluent was H₂SO₄ 5 mM with an isocratic flow rate of 0.6 mL/min. No internal standard was included. Quantification was performed by the use of standard curves with correlation coefficient R² > 0.999.

Short chain fatty acids acetate, propionate, butyrate together with lactate and succinate were quantified in aliquots of supernatants previously filtered through a Millipore 0.45 μm pore-size filter (Billerica, MA, USA) by HPLC chromatography. Quantification was conducted on a HPLC Acquity equipped with an Aminex HPX-87H 300 × 7.8 mm (BioRad) column under conditions defined by manufacturer. Detection was achieved by a refractive index detector. The eluent was H₂SO₄ 5 mM at an isocratic flow rate of 0.6 mL/min.