Fig. 2.

Addition of lithium acetate to LC-mobile phases enhances ionization. Reduced O-glycans from mouse tracheal epithelial cells (mTECs) were separated on a PepMap Acclaim C18 column (75 μm × 15 cm, 2 μm pore size) using three different mobile phase pairs (Buffers A and B) on a Dionex UltiMate 3000 coupled to Thermo Velos Pro ITMS. A, the total current chromatogram and extracted ion chromatograms (B) demonstrate baseline separation of permethylated O-glycans using common proteomics buffers (Formic acid/Acetonitrile). C, observed alkali metal adduct ions for the three mobile phase conditions tested demonstrated optimal ionization and adduct formation in 0.02% acetic acid containing 1 mM lithium acetate. D, MS/MS fragmentation of two glycan isoforms are shown.