Phenylalanine functionalized zwitterionic monolith for hydrophobic interaction electrochromatography

Area of Science:

• Analytical Chemistry
• Separation Science
• Materials Science

Background:

• Hydrophobic interaction chromatography (HIC) and capillary electrochromatography (CEC) are crucial for separating complex mixtures.
• Developing novel stationary phases with tunable properties is essential for advancing chromatographic techniques.
• Zwitterionic materials offer unique separation capabilities due to their dual charge characteristics.

Purpose of the Study:

• To synthesize and characterize a novel phenylalanine (Phe) functionalized zwitterionic monolith.
• To investigate the hydrophobic interaction and mixed-mode separation mechanisms of the developed monolith.
• To evaluate the performance of the monolith in capillary electrochromatography for diverse analytes.

Main Methods:

• Two-step synthesis: preparation of a glycidyl methacrylate-based polymer monolith followed by on-column Phe modification.
• Characterization of the monolith's properties, including hydrophobicity and surface chemistry.
• Capillary electrochromatography (CEC) experiments with varying mobile phase pH to assess separation mechanisms and analyte retention.
• Investigation of electroosmotic flow (EOF) behavior under different pH conditions.

Main Results:

• Successful preparation of a Phe-functionalized zwitterionic monolith with inherent hydrophobicity.
• Observation of typical reversed-phase (RP) chromatographic behavior with good hydrophobic interactions.
• Demonstration of switchable cathodic and anodic EOF by adjusting mobile phase pH.
• Evidence of dual mixed-mode separation mechanisms: RP/cation exchange and RP/anion exchange at different pH values.
• Versatile separation of neutral, basic, and acidic analytes achieved via CEC.

Conclusions:

• The Phe-functionalized zwitterionic monolith provides a versatile platform for complex separations.
• The material exhibits tunable hydrophobic and ion-exchange properties, enabling mixed-mode chromatography.
• This novel monolith is suitable for CEC applications, offering efficient separation of diverse analytes.