A Bidentate Amino Stationary Phase For Hydrophilic Interaction Chromatography

A bidentate amino stationary phase (SG-EDA) for hydrophilic interaction chromatography (HILIC) was synthesized through Michael addition with methyl acrylate (MA) to aminopropyl silica and amidation to the resulting esters with ethylenediamine (EDA). FTIR and element analysis measurements were carried out to confirm the successful synthesis of the SG-EDA phase. The chromatographic characteristics of the SG-EDA phase were investigated by exploring the retention behaviors of different types of probes including naphthalene, acrylamide, berberine, and p-hydroxybenzoic acid. It revealed that the SG-EDA phase demonstrated a typical HILIC characteristic. To explore the retention mechanism of the SG-EDA phase, the retention behaviors of four organic acids were investigated by varying the pH of mobile phases, organic solvent content, and ionic strength. The results disclosed that hydrophilic interaction contributed to their retention at high acetonitrile content while ion exchange played a more important role. Finally, a comparison of separation for four organic acids was obtained with an aminopropyl silica phase (SG-NH2) and SG-EDA phase.