Capillary zone electrophoresis at subzero temperatures. III. Operating conditions and separation efficiency

Area of Science:

• Analytical Chemistry
• Separation Science
• Electrophoresis

Background:

• Capillary zone electrophoresis (CZE) is a powerful separation technique.
• Joule heating can limit separation efficiency at ambient temperatures.
• Subambient temperatures offer potential advantages for CZE.

Purpose of the Study:

• To investigate the benefits of conducting capillary zone electrophoresis at subambient temperatures.
• To evaluate the impact of low temperatures on separation efficiency, reproducibility, and sample loading.
• To explore the extension of CZE scope through psychroelectrophoresis.

Main Methods:

• Utilized a Beckman P/ACE system with an auxiliary cooling system for temperatures down to -20°C.
• Defined average capillary temperature based on axial temperature gradient and coolant temperature.
• Analyzed proteins and peptides, including closely related peptides and beta-lactoglobulins A and B.

Main Results:

• Separation efficiency was enhanced at subambient temperatures due to decreased molecular diffusivity.
• Reproducibility of protein migration times achieved with an R.S.D. better than 2.3%.
• Increased capillary diameter (180 µm) allowed for 15x higher sample loading without resolution loss.
• Reduced protein-capillary wall interactions observed at low temperatures with high buffer concentrations.

Conclusions:

• Subambient and subzero temperatures significantly extend the capabilities of CZE.
• Psychroelectrophoresis offers improved separation efficiency, higher sample capacity, and reduced analyte-capillary interactions.
• The benefits justify the use of cooling systems for advanced CZE applications.