Abstract: An electrophoretic apparatus comprising: a first electrolyte chamber containing a first electrode; a second electrolyte chamber containing a second electrode; a first sample chamber disposed between the first and second electrolyte chambers and proximate to the first electrolyte chamber; a second sample chamber disposed between the first sample chamber and the second electrolyte; three ion-permeable barriers separating the first electrolyte chamber, the first sample chamber, the second sample chamber, and the second electrolyte chamber, respectively, wherein the ion-permeable barriers impede convective mixing of the contents in each of the respective chambers; a first electrolyte reservoir and a second electrolyte reservoir in fluid communication with the first and second electrolyte chambers, respectively; a first sample reservoir and a second sample reservoir in fluid communication with the first and second sample chambers, respectively; means adapted for communicating a first electrolyte and a second elect