Surface-bonded ionic liquid stationary phases in high-performance liquid chromatography--a review

Area of Science:

• Analytical Chemistry
• Separation Science
• Materials Science

Background:

• Ionic liquids (ILs) are ionic, nonmolecular solvents with unique properties like low vapor pressure and high thermal stability.
• IL-modified silica, known as surface-confined ionic liquids (SCILs), are emerging as advanced stationary phases for high-performance liquid chromatography (HPLC).
• Over 21 SCIL stationary phases have been developed, demonstrating differential behavior and reduced free-silanol activity.

Purpose of the Study:

• To review the current state-of-the-art of SCIL stationary phases in HPLC.
• To summarize the preparation methods, chromatographic behavior, and analytical performance of SCIL phases.
• To highlight the potential of SCILs as multimodal stationary phases.

Main Methods:

• Review of literature on the preparation of SCIL stationary phases.
• Analysis of chromatographic behavior and separation mechanisms of SCIL phases.
• Evaluation of the analytical performance of SCILs for various analyte types.

Main Results:

• SCIL stationary phases exhibit unique separation capabilities, even for neutral solutes in reversed-phase mode, despite their charged nature.
• These phases demonstrate low free-silanol activity, contributing to improved chromatographic performance.
• The development of SCILs offers potential for multimodal separation capabilities.

Conclusions:

• SCIL stationary phases represent a significant advancement in HPLC technology.
• Their ability to separate diverse analytes, including neutral compounds, underscores their versatility.
• SCILs hold considerable promise for developing next-generation multimodal chromatographic separations.