Capillary electrophoretic separations of proteins using nonionic surfactant coatings

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Capillary zone electrophoresis (CZE) is a powerful separation technique.
• Protein adsorption and electroosmotic flow (EOF) can hinder CZE efficiency and reproducibility.
• Surface modification of capillaries is crucial for improving CZE performance.

Purpose of the Study:

• To develop a stable and effective capillary coating for protein separation in CZE.
• To reduce protein adsorption and electroosmotic pumping in coated capillaries.
• To enhance the selectivity and efficiency of protein separations by controlling pH without affecting flow rate.

Main Methods:

• Capillary preparation involved silica surface derivatization with octadecylsilane.
• A nonionic surfactant layer was deposited from an aqueous solution above its critical micelle concentration.
• Protein separations were performed using the modified capillaries in a capillary zone electrophoresis system.

Main Results:

• The nonionic surfactant coating significantly reduced protein adsorption.
• Electroosmotic pumping was decreased 5-8 fold, leading to improved separation efficiency.
• The coating demonstrated stability and reproducibility across a pH range of 4-11.
• Protein separations were achieved quickly with good recovery rates.

Conclusions:

• Nonionic surfactant coated capillaries provide a robust and reproducible method for protein separation via CZE.
• The hydrophilic coating effectively mitigates protein adsorption and controls electroosmotic flow.
• This approach allows for pH-dependent selectivity adjustments without compromising separation flow rates, enhancing analytical capabilities.