Abstract: A capillary electrophoresis method and apparatus (10) are disclosed in which pressure or vacuum is selectively applied to an outlet end (16) of the capillary tube (12) during sample loading, sample separation and sample mobilization past a detector (34). The vacuum can be used to load a sample mixture from the reservoir (20) quickly into the capillary tube (12), and then also move the sample quickly toward a detector (34) once it has been separated. When a voltage is applied across the capillary tube (12) to effect separation of analytes in the mixture sample, the pressure or vacuum can be selectively controlled as desired to either augment or oppose the effects of electroosmotic flow, and thereby enhance the sample separation. The pressure or vacuum can be adjusted during any phase of the operation and feedback circuitry (110) can be employed to control the flow rate of a sample through the capillary tube automatically.