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Enhancement of electroosmotic flow using zwitterionic additives
Amy M MacDonald1, Mary A W Sheppard, Charles A Lucy
1Department of Chemistry, University of Alberta, Gunning/Lemieux Chemistry Centre, Edmonton, Alberta, Canada.
Electrophoresis
|November 8, 2005
Summary
Zwitterionic additives significantly enhance electroosmotic flow (EOF) in silica capillaries without increasing buffer conductivity. The EOF increase is concentration-dependent and influenced by the zwitterion
Area of Science:
- Analytical Chemistry
- Separation Science
- Physical Chemistry
Background:
- Electroosmotic flow (EOF) is crucial for capillary electrophoresis (CE) separations.
- Modulating EOF without altering buffer conductivity is desirable for method optimization.
- Zwitterions are potential additives for controlling EOF.
Purpose of the Study:
- To investigate the effect of zwitterionic additives on EOF in bare silica capillaries.
- To determine the relationship between zwitterion structure and EOF enhancement.
- To understand the factors influencing EOF modulation by zwitterions.
Main Methods:
- Capillary electrophoresis (CE) experiments were conducted.
- Zwitterionic additives with varying structures were introduced into the running buffer.
- EOF magnitudes were measured at different zwitterion concentrations and conditions.
Main Results:
- Zwitterionic additives increased EOF by up to 69% without increasing conductivity.
- EOF enhancement showed a linear correlation with zwitterion concentration.
- The number of methylene groups in zwitterions influenced EOF enhancement.
- Specific zwitterion endgroups and amine functionality affected EOF modulation.
Conclusions:
- Zwitterionic additives are effective for enhancing EOF in CE.
- The structure of zwitterions, including chain length and endgroups, dictates their impact on EOF.
- EOF enhancement is predictable based on zwitterion properties and buffer composition.