Hydrolytically stable, low-p/ isoelectric membranes have been synthesized from low-p/ ampholytic components, poly(vinyl alcohol), and a bifunctional cross-linker, glycerol-1,3-diglycidyl ether. The low-p/ ampholytic components used contain one amino group and at least two weakly acidic functional groups. The acidic functional groups are selected such that the p/ value of the ampholytic component is determined by the pK(a) values of the acidic functional groups. When the concentration of the ampholytic component incorporated into the membrane is higher than a required minimum value, the p/ of the membrane becomes independent of variations in the actual incorporation rate of the ampholytic compound. The new, low-p/ isoelectric membranes have been successfully used as anodic membranes in isoelectric trapping separations with pH < 1.5 anolytes and replaced the hydrolytically less stable polyacrylamide-based isoelectric membranes. The new low-p/ isoelectric membranes have excellent mechanical stability, low electric resistance, good buffering capacity, and long life time, even when used with as much as 50 W power and current densities as high as 33 mA/cm(2) during the isoelectric trapping separations.