Abstract: The electroosmotic velocity of an electrolyte is determined by displacing the electrolyte which fills a capillary tube by a second electrolyte which has the same composition as the first electrolyte but of a different concentration. The current flowing through the electrolyte is monitored until the current value becomes constant, indicating that all of the first electrolyte has been replaced by the second electrolyte. The time required for the first electrolyte to be entirely replaced by the second electrolyte is therefore measured to yield the electroosmotic velocity. Any components of samples in the electrolyte can also be detected by a detector to measure its actual velocity. Such actual velocity and the electroosmotic velocity of the electrolyte as a whole enables the electrophoretic mobility of the sample component to be determined. This method also enables the measurement of migration rates of micelles.

Abstract: A capillary tube has a structure in its wall that permits ions to flow but no substantial amount of electrolyte to move therethrough. The structure therefore permits electrical contact between the electrolyte inside the tube and the outside environment without diluting the electrolyte. The structure forms only a small part of the side wall so that the tube retains its structural integrity and can be used in electrophoresis without requiring structural support. In the preferred embodiment, the structure is formed by drilling a hole in the side wall, filling the hole with glass powder and fused silica and heating the mixture to form a frit structure to plug the hole. The frit structure permits ions to flow but substantially no electrolyte to move therethrough. Electrophoretic samples exiting from the end of the tube are not diluted and can be continuously collected, such as on top of a moving plate.