Studies of electroosmotic flow in non-aqueous capillary electrophoresis

An investigation of the effects of many experimental factors on electroosmotic flow (EOF) in non-aqueous capillary electrophoresis (CE) was performed. The effects of applied voltage, organic solvents and organic salts as running buffer components, and various rinsing protocols are presented and discussed. The magnitude of EOF in CE when a non-aqueous solvent is employed is proportional to the ratio of dielectric constant to viscosity (ε_r/η) and the applied voltage. Furthermore, EOF decreases with the addition of less polar organic solvents. Rinsing the column with sodium silicate solution seems to be very effective in regenerating the capillary in non-aqueous CE. Efforts to improve (increase) EOF in non-aqueous CE by adding the organic salts were not successful. The control of EOF by applying radial fields was also studied. With regard to the latter, experimental results in aqueous CE with low pH buffer solution were in good agreement with previous reports. However, there was no measurable effect on EOF by radial fields when non- aqueous running buffers were employed. Effects of buffer pH on EOF control by an applied radial voltage in aqueous CE are also discussed.