In ion-exclusion separations, Donnan exclusion causes strong acids to elute in the void volume of the column. Weak acids that are protonated in the acidic eluent are not subject to Donnan exclusion and penetrate into the pores of the resin. Separation is accomplished by differences in pKa, size, and hydrophobicity. Use Thermo Scientific™ Dionex™ IonPac™ ICE Ion Exclusion Columns for separations of aliphatic organic acids and alcohols in complex samples and monitoring trace levels of borate in high-purity water.