FLOW COUNTERBALANCED CAPILLARY ELECTROPHORESIS

A new approach for increasing the efficiency and resolving power of capillary electrophoresis is presented. This approach utilizes a pressure-induced counterflow to actively retard, halt, or reverse an analyte's electrokinetic migration through a capillary. By retarding, halting, or moving the analytes back and forth across the detection window, one effectively keeps the analytes of interest in the separation field much longer than under normal separation conditions, thereby increasing both the efficiency and the resolving power of the separation. With this system, separation efficiencies of 17.3 million plates have been achieved with fluorescently labeled amino acids in 8 b. Separation efficiencies of this magnitude allow one to resolve compounds with electrophoretic mobility differences of 1 X 10(-7) cm2/s. This is 1 order of magnitude lower than with conventional capillary zone electrophoresis.