Optimization of Resolution in Capillary Zone Electrophoresis: Effect of Solute Mobility and Buffer pH

Abstract

A reformulated version of the resolution equation in CZE that explicitly relates resolution to migration time is presented. Selectivity and resolution are enhanced with increasing migration time if the increase in time is a result of independent manipulation of electroosmotic flow. If the increase in migration time is a result of simultaneous changes in electroosmotic flow and electrophoretic mobility, selectivity and resolution deteriorate with increasing migration time. Optimum resolution for organic acid isomers is attained at a pH value that is about 0.3 units lower than the average pK of the two acids, even though selectivity continuously increases with decreasing pH. Both selectivity and resolution deteriorate with increasing electroosmotic flow in the same direction as electrophoretic mobility, however, selectivity is more sensitive than resolution to such changes.