High-capacity polymer-based weak cation exchanger for ion chromatography

A novel polymer-based weak cation exchanger functionalized with dicarboxyl groups is described. The stationary phase was synthesized through radical-initiated copolymerization of maleic anhydride and glycidyl methacrylate onto porous poly(styrene-divinylbenzene) microspheres, followed by hydrolysis to yield carboxylate groups. The resultant cation exchanger enables simultaneous isocratic separation of alkali and alkaline earth metals (including NH₄⁺) using a single strong acid eluent. High column efficiencies were achieved (e.g., 31,900 and 35,800 plates per meter for Na⁺ and K⁺, respectively) and high capacity was obtained (4.80 mmol/column or 1.93 μmol/mm³). The column also demonstrated good selectivity toward organic amines and other metal ions. The method was successfully applied to the determination of cations in tap water and beer matrices, with recoveries ranging from 92.7% to 109.4%, highlighting its potential for complex sample analysis.