Prepared Polymethacrylate-Based Monoliths for the Separation of Cations by Non-Suppressed Capillary Ion Chromatography

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This paper describes a novel analytical system for non-suppressed capillary ion chromatography. Methacrylate monolithic columns were prepared from silanized fused-silica capillaries of 320 µm i.d. by in situ polymerization of glycidyl methacrylate and ethylene dimethacrylate in the presence of 1,4-butanediol, 1-propanol and water as the porogen solvents. The introduction of cation-exchange sites was achieved by sulfonating the matrix with sodium sulfite to produce total cation-exchange capacities in the range of 45-105 μequiv/mL for a 25 cm column. The conditions (concentrations of sodium sulfite solution, reacting time and modified flow rate) of sulfonation were optimized. The hydrodynamic and chromatographic performances were estimated. Coupled with a conductivity detector, a capillary ion chromatography system was set up with the prepared column. Finally, the resultant column was used for the separations of five common univalent cations (Li(+), Na(+), NH4(+), K(+) and Cs(+)) using methanesulfonic acid as the eluent and four divalent cations (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) by non-suppressed capillary ion chromatography; the chromatographic parameters were further researched.