Abstract: Solid phases such as capillary tubes or solid supports used in chromatography, and in particular electrophoresis, are treated with oxidizing or reducing agents as needed to maintain or restore surface electrical charges or the lack thereof, which become modified during electrophoresis as a result of action by system components in the separation medium or the solutes themselves. The treatment is used as a means of achieving reproducible electroosmotic bulk flow when desired or suppressing unwanted electroosmotic flow arising due to the accumulation of charges on the surface. The result is improved reproducibility of retention times and component separation.

Abstract: Capillary zone electrophoresis systems are separated into two zones, one primarily for electroosmotic fow generation and the other dominated by electrophoretic effects, by the use of appropriately selected capillary materials for each region. Detection of the solute zones occurs in the electrophoretic region, minimizing or eliminating entirely the entry of the solutes into the electroosmotic region. The benefit acheived is avoidance or minimization of the adsorption of charged solutes by the capillary wall in electroosmotic flow.