Novel cationic coating agent for protein separation by capillary electrophoresis(†)

Area of Science:

• Analytical Chemistry
• Separation Science
• Biochemistry

Background:

• Capillary electrophoresis (CE) is a powerful separation technique.
• Controlling electroosmotic flow (EOF) is crucial for effective CE separations.
• Novel surfactants can modify capillary surfaces to influence EOF.

Purpose of the Study:

• To evaluate a novel positively charged surfactant, N-dodecyl-N,N-dimethyl-(1,2-propandiol) ammonium chloride, for dynamic capillary coating.
• To investigate the influence of surfactant concentration and buffer conditions on EOF and protein separation.
• To compare the novel surfactant's performance with commercial cationic surfactants and apply the method for real-world sample analysis.

Main Methods:

• Dynamic coating of silica capillary inner walls with the novel surfactant.
• Capillary electrophoresis experiments to study EOF and protein separation.
• Analysis of protein mixtures (ribonuclease A, cytochrome c, lysozyme, myoglobin).
• Comparison with cetyltrimethylammonium bromide and dodecyltrimethylammonium bromide.
• Application of the method for lysozyme determination in a cheese sample.

Main Results:

• A low concentration (0.1 mM) of the surfactant reversed EOF.
• Higher surfactant concentrations were required for effective separation of basic and neutral proteins.
• Optimal separation conditions were established using 10.0 mM surfactant in 100 mM sodium acetate buffer (pH 5.5).
• The developed method achieved limits of detection and quantification for lysozyme at 0.9 and 3.0 mg/L, respectively.
• Lysozyme was quantified in a cheese sample at 167.3 ± 10.3 mg/kg.

Conclusions:

• The novel surfactant provides effective dynamic coating for silica capillaries, enabling control over EOF.
• The method allows for selective separation of diverse proteins, including basic and neutral types.
• The developed CE method is suitable for quantifying specific proteins like lysozyme in complex food matrices.