Preparation, Characterization and Chromatographic Evaluation of Nickel Oxide Deposited Silica Stationary Phase in Hydrophilic Interaction Liquid Chromatography

Abstract

Nickel oxide deposited silica (NiO@SiO2) stationary phase was prepared by liquid-phase deposition (LPD) and characterized by field emission scanning electron microscope (FE-SEM), energy dispersive spectrum (EDS), specific surface, and pore size analysis. Then the chromatographic performances of NiO@SiO2 and SiO2 were compared under hydrophilic interaction liquid chromatography (HILIC) mode. The effects of acetonitrile (ACN) content, pH, salt concentration in the mobile phase, and column temperature on the retentions of nitrogenous polar compounds were investigated systemically. Imidazoles, purines, pyrimidines, and nucleosides compounds exhibited stronger retentions on NiO@SiO2 than those on SiO2, under the same chromatographic conditions. The results showed that NiO@SiO2 and nitrogenous analytes exhibited multiple interactions, including partitioning, absorption, ion-exchange, electrostatic attraction, and coordination, while there existed no coordination between SiO2 and nitrogenous analytes. In addition, the relative standard deviation (RSD%) of the retention times for four analytes eluted after 6000 column volumes and on three batches of NiO@SiO2 was less than 8.3%, indicating the good stability and repeatability of the NiO@SiO2 column. NiO@SiO2 was applied to the separation of nitrogenous polar compounds from complex actual samples, which indicated the promising application prospect of NiO@SiO2 stationary phase in the actual sample separation in HILIC mode.

Keywords: Nickel oxide deposited silica (NiO@SiO2), Hydrophilic interaction liquid chromatography (HILIC), Coordination, Nitrogenous compounds