Preparation of a low bleeding polar stationary phase for hydrophilic interaction liquid chromatography

A common drawback of silica-based polar stationary phase is obvious bleeding, probably resulting from silica dissolution in water attracted onto silica gel. Recently we have reported a polyvinyl alcohol (PVA) encapsulated silica gel stationary phase for hydrophilic interaction liquid chromatography (HILIC), which demonstrated good chromatographic performance. Although PVA coating outside could shield SiO2 inside from erosion by aqueous solution to a certain degree, obvious bleeding of such phase was still observed. To eliminate or reduce the bleeding level of the phase, fabricating multi-layers of PVA coating crosslinked with glutaraldehyde onto silica gel is performed (PVA-GA-Sil). ∼20-fold decrease of the bleeding for PVA-GA-Sil can be achieved relative to bare silica gel, which is much lower than (or comparable to) commercial HILIC phases. PVA-GA-Sil also showed chromatographic performance and demonstrated superiority to commercial columns operated at gradient mode.