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Study of electroosmotic flow in packed capillary columns.
Michał Szumski1, Bogusław Buszewski
1Department of Environmental Chemistry and Ecoanalytics, Faculty of Chemistry, Nicolas Copernicus University, 7 Gagarin Street, 87-100 Toruń, Poland.
Journal of Chromatography. A
|April 7, 2004
Summary
This study reveals no direct link between silanol activity and electroosmotic flow (EOF) in C18 phases. Alkylamide phases show reduced EOF at high pH due to hydrolytic pillow formation.
Area of Science:
- Analytical Chemistry
- Chromatography
Background:
- Understanding the electroosmotic flow (EOF) is crucial for optimizing chromatographic separations.
- The properties of stationary phases significantly influence EOF generation.
Purpose of the Study:
- To investigate the relationship between stationary phase structure and generated electroosmotic flow (EOF).
- To analyze the impact of stationary phase characteristics, mobile phase composition, and pH on electroosmotic mobility (microEOF).
Main Methods:
- Synthesis and characterization of C18 stationary phases with varying architectures (monomeric/polymeric, end-capped/un-capped).
- Evaluation of alkylamide (AP) bonded phases with different alkyl chain lengths (C1-C18).
- Assessment of silanol activity using the Galushko test.
- Systematic variation of mobile phase composition and pH to study EOF behavior.
Main Results:
- No direct correlation was found between silanol activity and electroosmotic mobility for C18 phases.
- Alkylamide (AP) phases exhibited decreased EOF at elevated pH levels.
- The observed EOF deterioration in AP phases was attributed to a hydrolytic pillow effect caused by water sorption.
Conclusions:
- Stationary phase structure, particularly alkyl chain length and bonding type, critically affects EOF.
- Silanol activity is not a reliable predictor of EOF for C18 phases.
- Hydrolytic pillow formation in AP phases at high pH impacts EOF, necessitating careful mobile phase selection.