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Separation of neutral compounds by capillary electrokinetic chromatography using polyethyleneimine as replaceable
Electrophoresis
|October 7, 1998
Summary
Polyethyleneimine (PEI) effectively separates phenols in electrokinetic chromatography by acting as a charged phase. This method relies on interactions with hydroxyl groups for selective separation of uncharged compounds.
Area of Science:
- Analytical Chemistry
- Chromatography
Background:
- Electrokinetic chromatography (EKC) is a powerful separation technique.
- Developing effective stationary phases is crucial for EKC applications.
Purpose of the Study:
- To investigate the use of Polyethyleneimine (PEI) as a pseudostationary phase in EKC.
- To analyze the separation of uncharged mono- and oligophenols using PEI.
Main Methods:
- EKC was performed in fused-silica capillaries coated with PEI.
- Separations were conducted in 2-(N-morpholino)ethanesulfonic acid (MES) buffer at pH 7.0.
- Varying concentrations of PEI (up to 0.70% w/v) were used as the pseudostationary phase.
Main Results:
- PEI effectively retarded solutes based on the number and position of hydroxyl groups.
- Methyl groups had minimal influence on the separation.
- High resolution (190,000 plates/meter) was achieved with 0.25-0.30% PEI concentrations.
- Relative retention (rho) values ranged from 0.33 to 0.53 at 0.70% PEI.
Conclusions:
- PEI serves as a viable positively charged pseudostationary phase for EKC.
- Separation selectivity is primarily driven by ion-dipole interactions between solute hydroxyl groups and PEI.
- This method offers high efficiency for separating phenolic compounds.