Alkali‐stable high‐p I isoelectric membranes for isoelectric trapping separations

Alkali‐stable, high‐p I isoelectric membranes have been synthesized from quaternary ammonium derivatives of cyclodextrins and poly(vinyl alcohol), and bifunctional cross‐linkers, such as glycerol‐1,3‐diglycidyl ether. The new, high‐p I isoelectric membranes were successfully applied as cathodic membranes in isoelectric trapping separations in place of the hydrolytically more labile, polyacrylamide‐based cathodic isoelectric membranes, and permitted the use of catholytes as alkaline as 1 M NaOH. The new high‐p I isoelectric membranes have shown excellent mechanical stability, low electric resistance and long life times, even when subjected to electrophoresis with current densities as high as 80 mA/cm 2 .