Comparative characterization of hydrophilic interaction liquid chromatography columns by linear solvation energy relationships

Abstract

22 commercially available and home-made stationary phases with different surface modifications were compared under hydrophilic interaction liquid chromatographic (HILIC) conditions. The column set comprised neutral, basic, acidic, zwitterionic and mixed surface modifications. Retention data of 68 differently structured test solutes were acquired to generate retention models based on a linear solvation energy relationship (LSER) approach. A recently modified solvation parameter model with two additional molecular descriptors was evaluated in terms of its universal applicability when electrostatic forces are enabled in addition to predominant partition phenomena. The suggested method could not be confirmed to be a standardized way to characterize HILIC systems when different operating conditions are applied. However, the significant contribution of the recently introduced charge descriptors (D− and D+) on explaining the interactions within HILIC systems was confirmed. The solvation parameter model was found to be a useful tool in the course of column development, to affirm or dismiss the preceding educated guess on how certain immobilized ligands will behave. Acidic modified surfaces (stationary phases) exhibit a very small hydrogen bond acceptor property and are less versatile when it comes to an even distribution of solutes along the retention window. Furthermore, the results indicate that basic and neutral columns are more preferable for HILIC applications and might explain why only a limited variety of strong acidic modified HILIC columns, although found in literature, are available commercially.