Monolithic silica columns for HPLC, micro-HPLC, and CEC

Two types of monolithic silica columns derivatized to form an ODS phase, on e prepared in a fused silica capillary (SR-FS) and the other prepared in a mold and clad with an engineering plastic (poly-ether-ether-ketone) (SR-PEE K), were evaluated. The column efficiency and pressure drop were compared w ith those of a column packed with 5-mu m OBS-silica particles and of an ODS -silica monolith prepared in a mold and wrapped with PTFE tubing (SR-PTFE). SR-FS gave a lower pressure drop than a column packed with 5-mu m particle s by a factor of 20, and a plate height of 20 mu m at a linear velocity bel ow 1 mm/s, SR-PEEK showed higher flow-resistance than the other monolithic silica columns, but they still showed a minimum plate height of 8-10 mu m a nd a lower pressure drop than popular commercial columns packed with 5-mu m particles, The evaluation of SR-FS columns in a CEC mode showed much highe r efficiency than in a pressure-driven mode.