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Published on: September 19, 2018
Comparing capillary coatings for protein separation by capillary electrophoresis
Alisa Höchsmann1, Christina Sejling2, Laura Dhellemmes2
1Faculty of Chemistry, Aalen University, Aalen, Germany; Faculty of Science, University of Tübingen, Tübingen, Germany.
Analytica Chimica Acta
|May 26, 2026
Summary
Choosing the right capillary coating is key for effective intact protein separation. This study compares seven coatings, finding cationic coatings like DODAB offer superior separation efficiency compared to neutral ones, especially at higher voltages.
Area of Science:
- Analytical Chemistry
- Separation Science
- Biophysical Chemistry
Background:
- Intact protein separation via capillary electrophoresis (CE) demands optimized capillary coatings for high efficiency.
- A wide array of coatings and protocols necessitates direct performance comparisons under identical conditions.
Purpose of the Study:
- To systematically compare the separation performance of seven distinct capillary coatings for intact proteins.
- To evaluate the impact of electric field strength on separation efficiency across different coating types.
Main Methods:
- Electrophoretic experiments were conducted using five model proteins at varying electric voltages.
- Plate height (H) versus migration velocity was analyzed for seven capillary coatings: polyvinyl alcohol (PVA), polyethylene oxide (PEO), hydroxypropyl cellulose (HPC), linear polyacrylamide (LPA), PDADMAC-PSS, and dioctadecyldimethylammonium bromide (DODAB).
- Separation efficiency was assessed based on plate height, and the influence of protein chain stretching at high voltages was investigated.
Main Results:
- All coatings showed increased plate height with higher voltages, indicating better separation at lower voltages.
- Neutral coatings exhibited a non-linear increase in H at high voltages, leading to reduced efficiency due to protein chain stretching.
- Cationic coatings, particularly DODAB, demonstrated superior performance, with the ranking (best to worst): DODAB > HPC > μSIL-WAX > LPA > PEO > SMIL > PVA.
- Resolution is influenced by both separation efficiency and electroosmotic flow (EOF) magnitude relative to protein mobility.
Conclusions:
- Cationic coatings are advantageous for intact protein CE, mitigating efficiency loss at higher voltages compared to neutral coatings.
- The selection of a capillary coating should balance separation efficiency with the desired electroosmotic flow for targeted protein analysis.
- Dioctadecyldimethylammonium bromide (DODAB) emerged as the top-performing coating for intact protein separation efficiency in this study.
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