The present teachings provide a microfluidic apparatus comprising a body defining at least one channel that extends through said body, the channel including an inlet and an outlet; and an electrode positioned in proximity to the body and configured to provide an electrical field near the outlet of the channel to at least partially confine an eluted sample component passing from the channel. The present teachings also provide an electrophoresis system, comprising a microfluidic chip defining a plurality of channels passing therethrough, each of the channels having an inlet and an outlet; a first electrode in electrical communication with the inlet of each of the channels; a second electrode in electrical communication with the outlet of each of the channels; and a third electrode in electrical communication with the outlet of each of the channels, wherein the third electrode is positioned to provide an electrical field to at least partially confine an eluted sample component passing from any of the channels. The present teachings also provide a method for confining a sample component eluting from a channel of a microfluidic chip, comprising generating an electrical field in proximity to an outlet of a channel in a microfluidic chip to at least partially confine an eluted sample component passing from the channel, thereby reducing distortion of the eluted sample component and mixing with an adjacent eluted sample component.