Electroosmosis . Electroosmosis refers to the movement of the buffer in the capillary under the influence of the electric field. The inner surface of a fused silica capillary is covered with silanol groups (Si-OH), which are ionized to SiO – at pH > 2. The negatively charged surface is counterbalanced by positive ions from the buffer, forming the so-called electric double layer. Under the influence of the electric field, the positive ions in the diffuse part of the double layer migrate towards the cathode; in doing so they entrain the waters of hydration, which results in electroosmotic flow. The equations of electroosmotic flow are identical to those developed for electrophoresis, as both