MOLDED RIGID POLYMER MONOLITHS AS SEPARATION MEDIA FOR CAPILLARY ELECTROCHROMATOGRAPHY - 2 - EFFECT OF CHROMATOGRAPHIC CONDITIONS ON THE SEPARATION

The effect of chromatographic conditions on the performance of monolit hic poly(butyl methacrylate-co-ethylene crylate-co-2-acrylamido-2-meth yl-1-propanesulfonic acid) columns in capillary electrochromatography has been studied. The now velocity was found to be proportional to the strength of the electric field and both the pH and the composition of the mobile phase. A column efficiency of 120 000 plates/m at the opti mum now velocity of 1.5 cm/min is achieved for all the monolithic capi llary columns of identical composition and porosity, regardless of the ir length, which varied from 30 to 120 cm. The polymeric separation me dium exhibits retention and selectivity properties similar to those of typical ODS packings for reversed-phase chromatography. In addition t o the ''classical'' use of monolithic capillary columns for the electr ochromatographic separation of small molecules in reversed-phase mode, larger styrene oligomers were also separated under isocratic elution conditions. In addition, the electroosmotically driven size exclusion chromatography of polystyrene standards with molecular weights up to 1 0(6) has been demonstrated for the first time.