Fluid Stabilization during Isoelectric Focusing in Cylindrical and Annular Columns

Abstract

The interest in fluid stabilization of focusing columns results from the attractive prospect of preparative isoelectric focusing as an alternative to chromatographic separations for downstream processing of proteins and pep-tides. In isoelectric focusing there is a variation of buffer composition, pH, conductivity, and temperature along the separation axis. The disturbing effects of the latter two parameters can be minimized using solid support media or gels. However, gravity-dependent convection and gravity-independent electroosmosis hamper focusing in free fluids in a complex way that prevents the scaling up of this process while maintaining the exquisite resolution of the analytical scale. The present study discusses methods for minimizing these disturbing effects in annular and cylindrical focusing columns of varying cross-sectional areas and internal geometries.