CAPILLARY ELECTROCHROMATOGRAPHY - A HIGH-EFFICIENCY MICRO-SEPARATION TECHNIQUE

Capillary electrochromatography (CEC) is a novel separation technique in which mobile phase transport through a capillary (50-200 mu m I.D.) packed with stationary phase particles is achieved by electroosmotic flow (EOF) instead of a pressure gradient as in HPLC. Electroosmotic f low allows the usage of smaller particles and longer columns than in H PLC because of the absence of backpressure. Separation is achieved by partitioning between mobile and stationary phase and-in the case of ch arged analytes-by differential electrophoretic mobilities. In the reve rsed-phase mode, capillary electrochromatography has the potential to yield efficiencies five to ten times higher than standard RP-HPLC. For this reason CEC has started to create high interest among chromatogra phers. This paper will discuss the theoretical background of CEC, demo nstrate the feasibility of CEC as a high-efficiency reversed-phase sep aration technique, compare theoretically achievable results to those o btained in practice and present fundamental studies on operational par ameters such as dependence of EOF and efficiency on pH and organic mod ifier content.