Effect of stationary phase hydrophobicity and mobile phase composition on the separation of carboxylic acids in ion chromatography

In a previous work, we studied the retention behavior of monovalent and div alent carboxylic acids on a highly cross-linked polystryene-divinylbenzene anion-exchange column (IonPac AS4A-SC) using a carbonate-based buffer, and a retention model was applied to the chromatographic data obtained. In this work we characterized the retention of carboxylates (formic, acetic, propi onic, lactic, pyruvic, oxalic, malonic, succinic, fumaric, maleic, tartaric , glutaric, adipic, malic, mucic, trans-beta-hydromuconic, trans,trans-muco nic acids) on a column with higher hydrophilicity (IonPac AS11) according t o analyte and stationary phase properties, using previously investigated el uent compositions and comparing the retention data obtained. Moreover, the effect of organic modifiers (CH3OH and CH3CN) in the eluent on the retentio n factors was also evaluated. The chromatographic data obtained on the IonP ac AS11 column were fitted by the retention model and allowed one to obtain and to compare ion-specific selectivity constants (parameters of the model ) with the ones obtained with the previous column. (C) 2000 Elsevier Scienc e B.V. All rights reserved.