It is generally accepted that partitioning is the main retention mechanism involved in hydrophilic interaction liquid chromatography (HILIC). However, secondary interactions, such as dipole-dipole and ion-exchange, can play an important role in the separation, leading to changes in selectivity. It is therefore essential to understand and characterize secondary retention mechanisms in order to make a judicious selection of the column. This article presents the results of a HILIC chromatographic characterization regime carried out on ten silica-based columns, including unmodified silica, amino, diol, ion exchanger and zwitterionic materials, and a Porous graphitic Carbon (PGC) column. Based on the HILIC characterization scheme developed by Tanaka’s group, the testing describes the structure-selectivity relationships between analytes and stationary phases. The retention properties investigated include the degree of hydrophilicity, the selectivity for hydrophilic and hydrophobic groups, positional selectivity, the anion and cation exchange properties and the evaluation of the stationary phase pH. The data were summarized as radar plots, which proved to be useful to distinguish the overall selectivity of the HILIC stationary phases and ultimately can be used as a column selection tool in HILIC method development.
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