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Published on: April 5, 2019
Mixed-mode reversed-phase and ion-exchange monolithic columns for micro-HPLC
Zhengjin Jiang1, Norman W Smith, Paul D Ferguson
1Pharmaceutical Sciences Research Division, King's College London, London, UK.
Journal of Separation Science
|July 31, 2008
Summary
Researchers developed novel mixed-mode monolithic materials for capillary LC. These materials offer improved mechanical stability and satisfactory separations for various compounds, demonstrating potential for micro-HPLC applications.
Area of Science:
- Analytical Chemistry
- Separation Science
- Materials Science
Background:
- Capillary liquid chromatography (LC) requires robust stationary phases for efficient separations.
- Monolithic materials offer advantages in terms of permeability and surface area for chromatography.
- Developing mixed-mode materials combines different separation mechanisms for enhanced selectivity.
Purpose of the Study:
- To fabricate and characterize novel RP/ion-exchange mixed-mode monolithic materials for capillary LC.
- To evaluate the mechanical stability and separation performance of these monoliths for micro-HPLC.
- To investigate the separation mechanisms, including ion-exchange interactions, of the developed monolithic columns.
Main Methods:
- Fabrication of monolithic materials via copolymerization of PEDAS, SEMA, and EDMA within capillaries.
- Surface deactivation using 3-(trimethoxysilyl)propyl methacrylate (gamma-MAPS).
- Characterization using mercury intrusion porosimetry, SEM, and micro-HPLC.
- Separation of neutral, acidic, and basic compounds under varying mobile phase conditions.
Main Results:
- Monoliths prepared with a small amount of ethylene glycol dimethacrylate (EDMA) exhibited improved mechanical stability.
- Satisfactory separations of diverse compounds were achieved using the fabricated capillary LC columns.
- Comparative studies revealed different selectivities for basic compounds, influenced by material composition and mobile phase pH, indicating ion-exchange interactions.
Conclusions:
- The developed RP/ion-exchange mixed-mode monolithic materials are suitable for micro-HPLC applications due to their enhanced mechanical stability.
- The materials demonstrate effective separation capabilities for a range of analytes.
- Ion-exchange interactions play a significant role in the separation of basic compounds, modulated by mobile phase pH.
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