Capillary electrophoresis using core-based hyperbranched polyethyleneimine (CHPEI) static-coated capillaries

Area of Science:

• Analytical Chemistry
• Separation Science
• Materials Science

Background:

• Capillary electrophoresis (CE) relies on electroosmotic mobility (EOF) for analyte migration.
• Controlling EOF is crucial for optimizing CE separation efficiency and reproducibility.
• Surface modification of fused-silica capillaries is a common strategy to tune EOF.

Purpose of the Study:

• To investigate the application of core-based hyperbranched polyethyleneimine (CHPEI) as a capillary coating in CE.
• To demonstrate the manipulation of electroosmotic mobility (EOF) using CHPEI coatings.
• To evaluate the performance of CHPEI-coated capillaries for the separation of various compounds.

Main Methods:

• Physically adsorbing CHPEI coatings onto bare fused-silica capillaries (BFS) via electrostatic interactions.
• Measuring EOF values across a pH range of 4.0-9.0.
• Assessing coating stability, reproducibility, and the impact of ionic strength.
• Utilizing coated capillaries for the separation of phenolic compounds, B vitamins, and basic drugs.

Main Results:

• CHPEI coatings significantly altered EOF, with reversal observed at pH > 6 due to excess negative surface charge.
• EOF magnitudes were reduced threefold compared to BFS capillaries, with high reproducibility (% RSD <= 2).
• Coated capillaries demonstrated good stability (% RSD = 0.3) and consistent pH dependence (% RSD = 0.5).
• Successful separation of diverse analytes within 20 minutes with excellent migration-time repeatability (< 0.7% intra-capillary, < 2% inter-capillary).

Conclusions:

• CHPEI coatings provide a robust and reproducible method for manipulating EOF in capillary electrophoresis.
• The unique 3-D architecture of CHPEI contributes to its effectiveness as a capillary coating.
• CHPEI-coated capillaries are suitable for the efficient separation of a wide range of analytes.