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Accurately describing weak analyte-additive interactions by capillary electrophoresis
Philip Britz-McKibbin1, David D Y Chen
1Department of Chemistry, University of British Columbia, Vancouver, BC, Canada.
Electrophoresis
|March 29, 2002
Summary
Accurate capillary electrophoresis (CE) models require corrections for dielectric changes caused by additives. This study introduces a relative dielectric factor to improve models for analyte-additive interactions, enhancing binding constant determination.
Area of Science:
- Analytical Chemistry
- Separation Science
- Physical Chemistry
Background:
- Capillary electrophoresis (CE) models often overlook non-viscosity changes in background electrolytes (BGE) caused by additives.
- Existing models assume dielectric properties remain constant, which can be inaccurate at high additive concentrations.
- Accurate modeling of analyte-additive interactions is crucial for determining binding constants and understanding separation mechanisms.
Purpose of the Study:
- To investigate the impact of dielectric property changes in the BGE on analyte electrophoretic mobility during CE.
- To develop and validate a correction factor for dielectric changes in CE models.
- To improve the accuracy of modeling weak analyte-additive interactions, particularly with hydroxypropyl-beta-cyclodextrin (HP-beta-CD).
Main Methods:
- Studied weak interactions between deoxyribonucleotides and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in a CE system.
- Analyzed binding isotherms for nonideality.
- Developed and applied a relative dielectric correction factor alongside a viscosity correction factor to normalize analyte mobilities.
Main Results:
- Observed significant nonideality in binding isotherms for deoxyribonucleotide-HP-beta-CD interactions.
- Demonstrated that high concentrations of HP-beta-CD alter the dielectric properties of the BGE, affecting analyte mobility.
- Found that incorporating a relative dielectric factor alongside a viscosity correction factor significantly improved model accuracy, increasing the correlation between predicted and measured mobilities.
Conclusions:
- Dielectric property changes in the BGE are significant and must be accounted for in CE models, especially for weak interactions or high additive concentrations.
- The developed relative dielectric correction factor enhances the accuracy of CE models for analyte-additive interactions.
- This improved modeling is vital for precise determination of binding constants and mobility values, advancing the fundamental understanding of CE separations.