Tsk gel gmpwxl column

Concentration and mass average molecular weight (M_w) of γ-PGA was determined by gel permeation chromatography (GPC). The GPC was equipped with a TSKgel GMPWxl column (300 × 7.8 mm, Tosoh Bioscience GmbH, Griesheim, Germany) and a TSKgel PWxl guard column (40 × 6 mm, Tosoh Bioscience GmbH, Griesheim, Germany). The column was eluted with 30 mM KNO₃ at 40 °C at a flow rate of 1.0 mL min⁻¹. Peaks were detected with the RI detector of the integrated EcoSEC HLC-8320GPC system (Tosoh Bioscience GmbH, Griesheim, Germany). Data analysis was performed with the software WinGPC UniChrom (PSS Polymer Standards, Service GmbH, Mainz, Germany). Poly(ethylene oxide) standards with peak molecular weights (M_p) in the range of 56 to 1015 kDa (PSS Polymer Standards, Service GmbH, Mainz, Germany) were used to create a calibration curve for molecular weight. γ-PGA sodium salt (cosmetic grade; kindly provided by Henkel AG & Co. KGaA, Düsseldorf, Germany) was used to create a calibration curve to determine concentrations. Culture broth was diluted 1:50 with distilled water and filtered with 0.2 μm filters (Bulk GHP Acrodisc 13 mm syringe filter, GHP membrane, N° 4567, Pall Life Sciences, Dreieich, Germany). 30 μL of the standards and of the filtrated samples were injected.

The molecular weights (MW) of EUP1 and EUP2 were determined by high-performance gel permeation chromatography (HPGPC). The HPGPC system was equipped with a TSK gel GMPWXL column (Tosoh Corporation, Yamaguchi Prefecture, Japan, 7.8 mm × 300 mm, 13 µm) and an RI-201H differential refractometer (Shodex China Co. Ltd., Shanghai, China) as the detector. The conditions were as follows: injection volume 20 μL, column temperature 35 °C, using distilled water (H₂O) at a flow rate of 1.0 mL/min. Dextrans of different molecular weights (T-180, T-2000, T-4600, T-7100, T-10000, T-21400, T-84400, T-133800, and T-2000000) were used as standards, from which a standard curve based on the following equation was established: $$\mathrm{logMW} = -0.867{\mathrm{t}}_{\mathrm{R}} + 13.302\left({\mathrm{R}}^2 = 0.9925\right)$$ where t_R is retention time.

The linkages and hydroxyl groups of the fractionated lignin from corn stover biomass were analyzed using 2D NMR and ³¹P NMR (Liu et al., 2019a (link); Meng et al., 2019 (link); Xu et al., 2022 (link)). The lignin molecular weight distribution before and after fermentation was analyzed by gel permeation chromatography (GPC). The analysis was carried out on a Waters e2695 system equipped with a variable 2489 UV/Vis detector at 280 and 254 nm and two tandem 30 cm × 7.8 mm TSKgel GMPWxl column (TOSOH, Tokyo). As alkaline solution can dissolve the lignin, 0.1 M NaOH was employed as a mobile phase with a flow rate of 1.0 ml/min (Liu et al., 2017 (link); Xu et al., 2022 (link)).