New Nickel Oxide Stationary Phase for Improved HILIC Separation

Researchers from Hubei Academy of Agricultural Sciences and Wuhan University in China have developed a new stationary phase for hydrophilic interaction liquid chromatography (HILIC) that utilizes nickel oxide deposited on silica. The team prepared the stationary phase using liquid phase deposition and characterized its chromatographic performance using various polar compounds and benzimidazoles as probes.

HILIC is a separation technique based on the interaction between polar analytes and a hydrophilic stationary phase. It involves the retention of polar compounds through partitioning, adsorption, ion-exchange, electrostatic attraction, and coordination interactions. In HILIC, the mobile phase is typically a high percentage of water and a low percentage of organic solvent, and the stationary phase is usually silica-based with polar functional groups such as amino or hydroxyl groups. This technique is particularly useful for the separation of highly polar and water-soluble compounds that are difficult to separate using traditional reversed-phase chromatography.

The study, published in Chromatographia, revealed that the nickel oxide deposited silica stationary phase exhibited hydrophilic retention behavior and employed multiple retention mechanisms including partitioning, adsorption, ion-exchange, electrostatic attraction, and coordination interactions (1). The coordination of nickel oxide electron-accepting sites and the electron-donating solutes resulted in mixed-mode retention on the stationary phase, which enhances chromatographic selectivity for analytes.

The study also found that the prepared stationary phase showed better separation effect and different selectivity compared to silica and commercial Zorbax NH₂ columns. Furthermore, the batch-to-batch reproducibility was acceptable with the relative standard deviations of probe retention of less than 9.89%.

The research suggests that the new nickel oxide deposited silica stationary phase could be very useful in HILIC separation, particularly for polar compounds. The improved chromatographic performance and selectivity of the new stationary phase may have applications in various fields such as pharmaceuticals, environmental analysis, and biochemistry.

Reference

(1) Guo, Y. J.; Peng, X. T.; Yu, Q. W.; Feng, Y. Q. Preparation, Characterization, and Chromatographic Evaluation of Nickel Oxide Deposited Silica Stationary Phase in Hydrophilic Interaction Liquid Chromatography. Chromatographia 2023, 86, 125–134. DOI: 10.1007/s10337-023-04235-6