Chromatographic Characterization of a New Cationic β-CD Based Stationary Phase Prepared by Dynamic Coating

Abstract

Cyclodextrin-based stationary phases are frequently used for separation of various isomers. The main reason for applying new cyclodextrin (CD) derivatives for HPLC stationary phases is the improvement of separation efficiency. This paper introduces a new stationary phase prepared by dynamic coating of ion-exchanger with a newly synthesized cationic derivative of β-cyclodextrin. This mono-substituted derivative of β-cyclodextrin contains two tetraalkylammonium groups in its side chain. Diverse sets of analytes were tested to reveal the separation potential of the derivatized stationary phase. This dynamically coated stationary phase exhibited mostly better selectivity and resolution than a commercial chemically bonded β-cyclodextrin stationary phase. Mixtures of analytes were baseline resolved in shorter analysis time. Furthermore, interactions participating in the retention mechanism were identified using a linear free energy relationship approach and ionic interaction study. Lower hydrophobicity and higher ability to interact as hydrogen bond donor affect retention on the coated stationary phase. Even though the ionic interaction study confirmed that the surface of the ion-exchanger was modified by dynamic coating, the ionic interactions still contributed to the retention mechanism on the coated stationary phase.