Fig. 2.

Influence of the potential applied to the ESI source on retention of UDP-sugars. Chromatogram obtained with a newly installed or regenerated PGC column (a); chromatogram obtained after 20-min utilization of the column connected to the ESI source of an Orbitrap mass spectrometer (b). Conditions: column regeneration was performed with 80 % acetonitrile in water containing 0.10 % trifluoroacetic acid for 20 min, the sample measurements were done with the gradient program described in the materials and methods section for HPLC-MS; detection, UV, 262 nm; sample. UDP-Gal (100 μmol L⁻¹) and UDP-Glc (100 μmol L⁻¹)