BONDED POLYMETHACRYLATE STATIONARY PHASES FOR OPEN-TUBULAR LIQUID-CHROMATOGRAPHIC AND ELECTROCHROMATOGRAPHIC SEPARATIONS

Using a new procedure developed in our laboratory for the preparation of thick polymethacrylate films bonded in fused silica capillaries, cr osslinked polymeric stationary phases were synthesized in situ in 25-m u m-i.d. capillaries. The effect of monomer and crosslinker concentrat ions on the resulting polymer film was studied by open tubular capilla ry electrokinetic chromatography (OTCEC) using p-hydroxy benzoates (pa rabens) as test solutes. Retention of analytes showed interesting tren ds versus monomer and crosslinker concentrations, exhibiting maxima at certain combinations rather than a continuous increase in capacity fa ctor with increasing concentration. Because the electroosmotic flow ca n arise from both exposed silica and polymer surfaces, the flow veloci ty did not exhibit an obvious trend versus monomer and/or crosslinker concentration. Open tubular liquid chromatographic (OTLC) separations were also achieved using head pressure as the driving force for bulk f low, without employing a high-voltage power supply or micro LC pump. ( C) 1998 John Wiley & Sons, Inc.