Polymer-coated cation exchangers in high-performance ion chromatography: preparation and application

Low-capacity cation-exchange stationary phases for ion chromatography were prepared by coating a vinyl-modified silica gel with polystyrene or poly(glycidyl methacrylate). Strong acid ion-exchange groups were formed by sulphonation with concentrated sulphuric acid or by ring opening of the polymer-coated silica gels with sulphite solution. Carbon-sulphur elemental analyses of the polymer-coated cation exchangers (PCCEs) were applied to determine the average polymer film thickness. The pH stability depended on the polymer film thickness. The PCCEs were stable in the pH range 0.5–9. The low-capacity PCCEs (capacities 18–91 μmol/g) were applied to determine alkali and alkaline earth metal ions in tap and mineral waters.