Zwitterionic imidazolium sulfonate functionalized polymeric monolith for mixed-mode HILIC/RPLC applications

Area of Science:

• Chromatography
• Materials Science
• Analytical Chemistry

Background:

• Increasing demand for separating complex samples necessitates advanced chromatographic materials.
• Existing stationary phases often struggle with the simultaneous separation of diverse analytes.
• Development of mixed-mode stationary phases offers a versatile solution for complex mixture analysis.

Purpose of the Study:

• To develop a novel monolithic stationary phase with both hydrophobic and hydrophilic functionalities.
• To create a mixed-mode material capable of efficiently separating polar and nonpolar compounds.
• To enhance the capabilities of chromatographic analysis for complex samples.

Main Methods:

• Synthesized a novel monolithic stationary phase using 3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium) propane-1-sulfonate (VBIPS) as monomer and pentaerythritol triacrylate (PETA) as crosslinker.
• Characterized the poly(VBIPS-co-PETA) monolith for mechanical strength, permeability, and interaction modes (hydrophilic, hydrophobic, hydrogen bonding, electrostatic).
• Evaluated column efficiency and separation capabilities for various polar and nonpolar analytes.

Main Results:

• The optimized poly(VBIPS-co-PETA) monolith demonstrated good mechanical strength and high permeability.
• The stationary phase exhibited multiple interaction modes, enabling the retention and separation of both polar (e.g., benzoic acids, nucleosides) and nonpolar (e.g., anilines, PAHs) substances.
• Achieved a high column efficiency of 83,330 plates/m for thiourea, indicating excellent separation performance.
• Effective separation of polar analytes was attributed to sulfobetaine-derived hydrophilicity, while nonpolar analyte separation was facilitated by π-π stacking interactions.

Conclusions:

• The developed zwitterionic imidazolium sulfonate-functionalized monolith successfully integrates hydrophobic and hydrophilic properties.
• This novel mixed-mode stationary phase enables efficient separation of both polar and nonpolar analytes under low backpressure.
• The material expands the range of available mixed-mode stationary phases and broadens detection capabilities for complex sample analysis.