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Chiral separations with coated and uncoated capillaries
M A Cuñat-Walter1, E Bossú, H Engelhardt
1Institut für Instrumentelle und Umweltanalytik, Saarbrücken, Germany.
Journal of Capillary Electrophoresis
|November 1, 1996
Summary
Capillary electrophoresis resolution is significantly impacted by electroosmotic flow (EOF) magnitude. Choosing coated capillaries for low analyte mobility and uncoated for high mobility optimizes chiral separations.
Area of Science:
- Analytical Chemistry
- Separation Science
- Chiral Separations
Background:
- Chiral resolution in capillary electrophoresis is critical for distinguishing enantiomers.
- Electroosmotic flow (EOF) magnitude significantly influences analyte migration and separation.
- Understanding analyte mobility relative to EOF is key for optimizing chiral separations.
Purpose of the Study:
- To investigate the influence of electroosmotic flow (EOF) on chiral resolution in capillary electrophoresis.
- To establish a rule of thumb for selecting capillary coatings based on analyte effective mobility and EOF.
- To correlate capillary type with achieved separation efficiencies for chiral compounds.
Main Methods:
- Analysis of chiral compounds using capillary electrophoresis.
- Manipulation of electroosmotic flow (EOF) through capillary coating selection (coated vs. uncoated).
- Measurement of analyte effective mobility and comparison to EOF magnitude.
Main Results:
- Capillary coatings significantly alter EOF, impacting chiral resolution.
- When analyte effective mobility is <50% of EOF, coated capillaries with suppressed EOF yield better resolution.
- When analyte effective mobility is >50% of EOF, uncoated capillaries provide better resolution due to longer migration distances.
Conclusions:
- Capillary coating selection is a critical parameter for optimizing chiral separations in capillary electrophoresis.
- A predictive rule of thumb based on analyte mobility relative to EOF can guide capillary and method selection.
- Minimizing solute-wall interactions enhances separation efficiency by maximizing analyte time within the capillary.