A positively charged porous graphitic carbon stationary phase for hydrophilic interaction liquid chromatography.

High chemical inertness of porous graphitic carbon particles (PGC) makes their surface modification rather difficult. Here a facile way is proposed to prepare a PGC stationary phase with quaternary ammonium-polyvinyl alcohol mixed functional groups for hydrophilic interaction liquid chromatography (HILIC) by generating a thin layer of polyvinyl alcohol (PVA) and poly(diallyldimethylammonium chloride) (DDAC) copolymer onto PGC particles. The phase shows obvious positively electrostatic character and typical HILIC character, exhibiting different selectivity relative to several HILIC phases and bare PGC. To the best of our knowledge, this is the first fully pH-stable, quaternary ammonium functionalized HILIC phase. It is much superior to silica-based HILIC phases in terms of wide pH tolerance (2.1–12.7) and low bleeding.