Turbomatrix 110 headspace sampler

Hydrogen and CO partial pressure (pH₂, pCO₂) were analysed by PP1 (Peak Performer 1, reduced gas analyser) by direct injection of 1 mL withdrawn headspace gas. Methane samples (2 mL) were withdrawn at the same time, injected into glass vials and stored at +2°C until analysis (within a maximum of 5 days) by GC (Perkin Elmer Ariel, Clarus 500 Gas Chromatograph equipped with a TurboMatrix 110 Headspace sampler). Elemental composition of the fluids at the end of the experiments was analysed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) (Spectro, Varian Vista AX with argon as carrier gas). The analytical error was ~4%. All ICP samples were prepared by withdrawing approximately 10 mL centrifuged and filtered liquid and adding 10 μL conc. HNO₃ (ultrapur, Merck).

1 mL of each post-fermentation media sample was combined with 200 µL of 5 M NaCl prior to analysis. Standard solutions of ethanol, acetaldehyde, formaldehyde, and methanol were made to the same volume and NaCl concentration. Gas chromatography (GC) headspace analysis was performed using a Clarus 600 with a Turbomatrix 110 Headspace sampler (PerkinElmer). Headspace sampling was performed with an oven temperature of 70 °C, injection time of 0.04 min, and column pressure of 16 psi, Samples were separated using a Restek Rxi-624Sil Column (30 m length, 0.32 mm ID) with He as a carrier gas at 2.5 mL/min at 90 °C, and a GC cycle time of 3.2 min.