The interstitial volume of ion-exchange columns

The relative interstitial volumes of ion-exchange columns were measured by equilibrating the columns with a standard solution, rinsing out the interstitial solution and determining the amount of solute in the rinsings. Solutions of three polyelectrolytes and of hydrochloric acid were used for this purpose. When hydrochloric acid was used, corrections were generally necessary because of the penetration of the acid into the resin. Satisfactory agreement was obtained among the various methods. Within the experimental error, the relative interstitial volume is independent of the exchangeable ion of the resin and of the mesh size. The interstitial volume decreases with decreasing crosslinkage.