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Chromatographic and electrophoretic migration parameters in capillary electrochromatography.
Anurag S Rathore1, Csaba Horváth
1Department of Chemical Engineering, Yale University, New Haven, CT, USA. anurag.s.rathore@pharmacia.com
Electrophoresis
|May 15, 2002
Summary
The chromatographic retention factor (k') from HPLC is not fully applicable to capillary electrochromatography (CEC) due to dual separation mechanisms. This study explores the limitations and alternative definitions for electrochromatographic retention factors.
Area of Science:
- Analytical Chemistry
- Separation Science
- Chromatography
Background:
- The chromatographic retention factor (k") is a key parameter in High-Performance Liquid Chromatography (HPLC) for quantifying solute retention and interaction with the stationary phase.
- Capillary Electrochromatography (CEC) employs both chromatographic and electrophoretic mechanisms for separation, creating a more complex system than traditional HPLC.
- Existing literature often applies the HPLC definition of k' to CEC, overlooking the distinct separation principles involved.
Purpose of the Study:
- To critically evaluate the applicability of the traditional chromatographic retention factor (k") in Capillary Electrochromatography (CEC).
- To discuss the challenges and limitations of using the HPLC-derived k' definition in the context of CEC's dual separation mechanisms.
- To present and discuss various definitions of electrochromatographic retention factors that account for both chromatographic and electrophoretic contributions.
Main Methods:
- Theoretical discussion and analysis of separation mechanisms in CEC.
- Comparison of the chromatographic retention factor (k") definition in HPLC versus its application in CEC.
- Review and presentation of alternative electrochromatographic retention factor definitions.
Main Results:
- The direct application of the HPLC chromatographic retention factor (k") definition is shown to be limited in CEC due to the combined effects of chromatographic and electrophoretic migration.
- The dual nature of CEC complicates the interpretation and utility of a single retention factor parameter derived solely from chromatographic principles.
- The interplay between chromatographic and electrophoretic forces significantly influences the overall migration rates of analytes in CEC.
Conclusions:
- A retention factor with all the attributes of k' in conventional chromatography cannot be definitively defined for CEC.
- Understanding the interplay of dual separation mechanisms is crucial for accurate characterization in CEC.
- The development and application of specific electrochromatographic retention factors are necessary for robust analysis in CEC.
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