Retention behaviour of strong acid anions in ion-exclusion chromatography on sulfonate and carboxylate stationary phases

Some factors influencing the retention of strong-acid anions on ion-exclusi on columns were investigated using columns with sulfonate and carboxylate f unctional groups. The nature of the functional group on the resin, the elue nt pH and the eluent ionic strength all significantly affected the retentio n and separation of these analytes. Retention was observed for all strong-a cid anions over the eluent pH range 2.2-5.7 and increased with both decreas ing eluent pH and increasing eluent ionic strength. Some separation of stro ng-acid anions was possible when using a resin with carboxylate functional groups. It has also been demonstrated that strong-acid anions are poor mark ers of column void volume for ion-exclusion chromatography. A more accurate value was obtained using the neutral polymeric material dextran blue. When using eluents of low ionic strength, poor or fronted peak shapes were obse rved, A mechanism for these observations is proposed that relates the shape to ionic strength changes across the peak, A system peak was encountered u nder most experimental conditions. The properties of this peak are discusse d and a cause for the system peak postulated. (C) 2000 Elsevier Science BN. All rights reserved.