Acrylamide-based monoliths as robust stationary phases for capillary electrochromatography

Area of Science:

• Analytical Chemistry
• Separation Science
• Polymer Chemistry

Background:

• Capillary electrochromatography (CEC) demands robust stationary phases for reproducible separations.
• Developing stable and tunable monolithic stationary phases is crucial for advancing CEC applications.

Purpose of the Study:

• To develop and optimize a reproducible synthesis method for rigid, macroporous polymer monoliths for CEC.
• To control monolith properties like pore size and hydrophobicity for tailored chromatographic performance.
• To evaluate the chromatographic behavior and reproducibility of the synthesized monolithic stationary phases.

Main Methods:

• Synthesis of macroporous polymers within capillaries using acrylamide-based monomers and a vinylsulfonic acid co-monomer.
• Adjustment of monolith pore size by varying ammonium sulfate concentration during polymerization.
• Modification of monolith hydrophobicity by incorporating co-monomers like alkyl chains.
• Evaluation of column performance using an electroosmotic flow (EOF) marker and a model mixture of aromatic compounds.

Main Results:

• Reproducible synthesis of CEC columns with high mechanical and chemical stability (nearly 100% success rate).
• Precise control over monolith pore size (50 nm to 1.3 µm) and hydrophobicity.
• Excellent run-to-run reproducibility (<1.5% standard deviation for retention times).
• Efficient separations with low plate heights (10-15 µm) even at high flow rates, exhibiting flat Van Deemter curves.

Conclusions:

• The developed method provides a reliable route to synthesize customizable monolithic stationary phases for CEC.
• The synthesized monoliths demonstrate superior stability, reproducibility, and chromatographic efficiency.
• These advanced monolithic columns show significant potential for high-performance separations in capillary electrochromatography.