Borate-containing background electrolytes to improve CE separation in bare capillaries

Area of Science:

• Analytical Chemistry
• Separation Science
• Capillary Electrophoresis

Background:

• Capillary electrophoresis (CE) relies on electroosmotic flow (EOF) for analyte migration in fused silica capillaries.
• Uncontrolled EOF can negatively impact separation efficiency and resolution in CE.
• Borate-containing buffers are investigated for their potential to modify capillary surface properties.

Purpose of the Study:

• To investigate the effect of borate-containing background electrolytes (BGEs) on zeta-potential and EOF in bare fused silica capillaries.
• To evaluate the utility of borate-modified EOF for improving CE separation performance, including capillary sieving electrophoresis (CSE).
• To demonstrate the application of borate-containing BGEs for size-separation of DNA fragments and proteins.

Main Methods:

• Utilized bare fused silica capillaries with various borate-containing background electrolytes (BGEs).
• Investigated the complexation of boric acid with polysaccharides and polyol bases.
• Analyzed the impact of borate concentration on zeta-potential and EOF.
• Performed size-separation of DNA fragments and proteins using CE and SDS CSE.

Main Results:

• Borate-containing BGEs significantly modify zeta-potential and suppress EOF by interacting with the fused silica capillary wall.
• Boric acid forms complexes with sieving matrices (polysaccharides) and polyol bases, influencing EOF.
• High boric acid concentrations effectively suppress or eliminate EOF; certain polyol bases can reverse EOF.
• Demonstrated successful size-separation of DNA and proteins using borate-containing BGEs in CE and SDS CSE.

Conclusions:

• Borate-containing BGEs offer a robust strategy to control and suppress EOF in bare fused silica capillaries.
• This EOF suppression enhances separation performance in CE and CSE for various analytes.
• Borate-containing BGEs provide a versatile tool for optimizing CE separations, including those for DNA and protein analysis.