Continuous-bed columns containing sol-gel bonded packing materials for capillary electrochromatography

Sol-gel bonded packing materials in continuous-bed columns have been prepar ed for capillary electrochromatography (CEC). Three packing materials were investigated: small-pore Spherisorb ODS1 (3 mu m, 80 Angstrom) with octadec yl as stationary phase, small-pore mixed-mode Spherisorb ODS/SCX (3 mu m, 8 0 Angstrom) with octadecyl and propyl sulfonic acid as stationary phases, a nd large-pore Nucleosil ODS (7 mu m, 1400 Angstrom) with octadecyl as stati onary phase. The characteristics of these columns were compared in terms of electroosmotic flow, efficiency, inertness, and retention factors. In cont rast to columns containing sol-gel bonded ODS, columns containing sol-gel b onded mixed-mode ODS/SCX generated nearly pH independent electroosmotic flo w (EOF) over pH 2-9. Columns containing sol-gel bonded large-pore ODS produ ced nearly three times lower reduced plate height than those containing sma ll-pore ODS. Efficiencies of 220,000 plates per meter and 175,000 plates pe r meter were obtained from columns containing sol-gel bonded 7 mu m, 1400 A ngstrom ODS and columns containing sol-gel bonded 3 mu m, 80 Angstrom ODS, respectively, which are among the highest reported efficiencies for continu ous-bed columns. In CEC, over one million plates per meter and pH independe nt EOF are expected from continuous-bcd columns containing sol-gel bonded 1 .5 mu m particles with large pores and mixed-mode stationary phases.