Abstract: An electrophoretic separation apparatus includes a capillary tube having a length, a cross section, an inlet and an outlet. A first reservoir containing a solvent and, upon injection, a solute is in fluid-flow communication with the inlet and a second reservoir containing at least a solvent is also in fluid flow communication with the outlet, the capillary thereby being filled at least with the solvent. A first power supply applies a direct voltage separation potential between the first and second reservoirs and along the length of the capillary to thereby establish an electrophoretic flow of the solute therethrough. A second power supply applies an alternating voltage upon the direct voltage, and the DC impedance and AC impedance values are determined and subtracted to provide a direct measurement of the electroosmotic flow.

Abstract: End-column detectors are provided in which either a sensing microelectrode or optical fiber is placed at the end of the separation capillary. Additionally, an alignment apparatus is provided to facilitate the manual or automated positioning of either type of sensing device relative to the end of the separation capillary. The invention provides detectors that are sensitive, reliable, and easy to construct and to operate.

Abstract: An electrophoretic separation apparatus includes a capillary tube having a length, a cross section, an inlet and an outlet. A first reservoir containing a solvent and, upon injection, a solute is in fluid-flow communication with the inlet and a second reservoir containing at least a solvent is also in fluid flow communication with the outlet, the capillary thereby being filled at least with the solvent. A first power supply means applies a separation potential between the first and second reservoirs and along the length of the capillary to thereby establish an electrophoretic flow of the solute therethrough. An electrically isolated conductor is juxtaposed to an external surface of the capillary tube and is connected to a second power supply. An electrostatic field is thereby applied across the cross section of the capillary tube to control the electroosmotic flow therein. The electrical isolation of the conductor prevents current flow between the power supply and the conductor.

Abstract: An electrophoretic separation apparatus includes a capillary tube having a length, a cross section, an inlet and an outlet. A first reservoir containing a solvent and, upon injection, a solute is in fluid-flow communication with the inlet and a second reservoir containing at least a solvent is also in fluid flow communication with the outlet, the capillary thereby being filled at least with the solvent. A first power supply means applies a separation potential between the first and second reservoirs and along the length of the capillary to thereby establish an electrophoretic flow of the solute therethrough. An electrically isolated plate is juxtaposed to an external surface of the capillary tube and is connected to a second power supply. An electrostatic field is thereby applied across the cross section of the capillary tube to control the electroosmotic flow therein. The electrical isolation of the plate prevents current flow between the power supply and the plate.

Abstract: Electrical and electrochemical end-column detectors are provided in which the sensing microelectrode is placed at the outlet of the separation capillary. The novel design minimizes the electrical interference caused by the applied high voltage during CZE separations, and provides for detectors that are easy to construct, sensitive, reliable, and easy to operate.