Hyperrez xp carbohydrate h ion exchange column

Organic acid and H₂ production were measured by gas chromatography, in accordance with Weghoff and Müller (2016) (link). Consumption of the substrates glucose and formate was determined by high performance liquid chromatography (HPLC, P680 HPLC Pump, ASI-100 Automated Sample Injector and thermostatted Column Compartment TCC-100, Dionex, Sunnyvale, CA, United States). For the sample preparation, cells were spun down by centrifugation at 13,000 rpm for 5 min and 200 μl of supernatant was filled into 2 ml vials containing 400 μl flat bottom glass insert (Agilent Technologies). A HyperREZ XP Carbohydrate H⁺ ion exchange column (Thermo Fisher Scientific, Waltham, MA, United States) was used for separation. For elution, degassed 5 mM sulfuric acid was used at a flow rate of 0.6 ml/min. The temperature of the oven was set at 65°C. 10 μl of sample was injected by auto-sampler and analyzed with a refractive index detector (RefractoMax 520; Dionex, Sunnyvale, CA, United States) set at 55°C.

The concentrations of H₂ were determined by gas chromatography as described previously [39 (link)]. The samples for H₂ determination were injected at 100 °C and separated on a ShinCarbon ST 80/100 column (2 m × 0.53 mm; Restek Corporation, Bellefonte, PA, USA). Nitrogen was used as the carrier gas with a head pressure of 400 kPa and a split flow of 30 ml/s. The samples were analyzed with a thermal conductivity detector at 100 °C and at an oven temperature of 40 °C. The concentrations of acetate and formate were determined by high-performance liquid chromatography [40 (link)]. For separation, a HyperREZ XP Carbohydrate H⁺ ion exchange column (Thermo Fisher Scientific, Waltham, MA, USA) was applied and degassed sulfuric acid (5 mM) was used as eluent at a flow rate of 0.6 ml/min. The oven was kept at 65 °C. 10 μl sample was injected by auto-sampler and analyzed with a refractive index detector (RefractoMax 520; Dionex, Sunnyvale, CA, USA) at 55 °C. Caffeate was determined photometrically at 312 nm using an extinction coefficient of 13.72 mM⁻¹·cm⁻¹ [26 (link)].