Dionex chromeleon 7 chromatography data system

Products of reactions described above (section Enzymatic Conversion of Xylooligosaccharides) were diluted in ultrapure water to 50–100 ppm concentrations depending on the sensitivity of substrate detection by HPAEC-PAD. Substrate depletion over the course of the reaction was followed using a DionexTM-5000⁺ system equipped with a Dionex^TM CarboPac^TM PA1 IC column and corresponding precolumn (Thermo Scientific, USA). The samples were eluted at 1 ml/min with eluent A (0.1 M NaOH) in a linear gradient toward an increasing proportion of eluent B (1 M NaOAc in 0.1 M NaOH). The gradient reached 21.7% B at 20 min after injection, 38% B at 25 min and 100% B at 27 min after which it was kept at 100% for 7 min. Data were analyzed using the Thermo Scientific Dionex Chromeleon 7 Chromatography Data System (version 7.2 SR4, Thermo Fisher Scientific). Corresponding xylooligosaccharides with three known concentrations were used to create a standard curve for each run. Integrated peak areas of the enzyme treated xylooligosaccharides were compared against the corresponding control reactions without the PDH enzyme.

All samples were analyzed on a Thermo Scientific/Dionex U3000 high-pressure liquid chromatography system equipped with a Thermo Scientific Dionex flow cell (cell volume: 2.5 µL, path length: 7 mm, pressure limit: 12 MPa, PN 6074.0360). The SEC column was pre-conditioned with mobile phase for 30 min before sample analysis. Samples were injected (6 μL, except as noted for linearity and LOD/LOQ determination) into a pre-conditioned column using a flow rate of 0.300 mL/min, resulting in a pressure of ≈180 bar. Isocratic elution was monitored for each injection using a total run time of 10 min. Peaks were detected by ultraviolet absorbance using the variable wavelength detector at a wavelength of 280 nm. Raw chromatograms were processed with Thermo Scientific Dionex Chromeleon 7 Chromatography Data System as described in the ESM.