In spite of great current popularity of polymer-based stationary phases for ion chromatography (IC), silica still has the advantage of high mechanical stability, absence of swelling or shrinking during the chromatographic process and resistance to any solvents and high temperatures.

One of the popular types of silica-based stationary phases for IC is so-called polyelectrolyte anion exchangers, which are obtained by covering silica or sulfonated silica particles with ionenes containing positively charged nitrogen atoms in the chain. This kind of charged polymer is held on the negatively-charged silica surface due to electrostatic interactions and such an approach results in high efficiency and good selectivity, which can be varied by changing the structure of the modifying ionene. In spite of all advantages of polyelectrolyte anion exchangers, their serious drawback is associated with low polymeric coating stability, which leads to the gradual decrease of the anion exchange capacity caused by the probable changes in ionene’s conformation and the washing of ionene off the surface.

In the present work we propose the novel type of silica-based anion exchangers with covalently attached polymeric coating, which is moved away form the active silica surface by diglycidyl ether spacers. The polymers used for coating should contain tertiary or secondary amino groups and the preliminary amination of silica is required.

With using branched polyethylenimine as a coating polymer such an approach provides the obtaining of the anion exchangers with increased efficiency up to 50000 theoretical plates per meter and good selectivity, which allows the separation of 10 anions in less than 30 minutes. Selectivity of the obtained anion exchangers can be varied easily by changing the structure of the attached polymer or the mobile phase pH. Another advantage of the proposed approach is high polymeric coating stability which is provided by its covalent attachment to the silica surface.