Evidence that Na+ in a sulfonate ion exchange resin exists in an adsorbed state. Its significance for the interpretation of NMR data in resins and cells.
The concentrations of total Na+ and of free Na+ were measured in solutions of Na+ polystyrene sulfonate (NaPSS). Free Na+ was determined using a Na+-sensitive glass electrode having a high degree of specificity for Na+. In a 5% PSS solution, 80% or more of the Na+ was not detected by the glass electrode and was adsorbed specifically onto the anionic sulfonate groups. The degree of adsorption increased with an increase in the concentration of PSS. These results were discussed in regard to the interpretation of NMR studies of Na+ in the cross-linked PSS resins (Dowex 50) and in living cells. The results show that the quadrupolar splitting of the Na+ NMR signal is caused by specific ionic adsorption onto fixed anionic sites and not by a diffuse charge gradient extending over large distances.
D000327:Adsorption; D000837:Anion Exchange Resins; D002412:Cations / Q000032:analysis; D002468:Cell Physiological Phenomena; D007475:Ion Exchange Resins; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D011137:Polystyrenes; D012117:Resins, Synthetic; D012964:Sodium / Q000032:analysis
D000837:Anion Exchange Resins; D002412:Cations; D007475:Ion Exchange Resins; D011137:Polystyrenes; D012117:Resins, Synthetic; C027972:Dowex; C003321:polystyrene sulfonic acid; D012964:Sodium