Capillary Storage Guidelines for Capillary Electrophoresis (CE)

Proper handling and storage of bare fused silica CE capillaries are important for maintaining reproducible results and maximizing capillary longevity. Residual buffers, samples, salts, and particulates left inside a capillary can contribute to fouling, decreased performance, increased operating pressure, and shortened capillary life.

Following a simple post-use cleaning and storage procedure can help remove contaminants and prepare the capillary for future analyses.

Recommended Storage Procedure

1. Filter All Solutions Before Use

All buffers, standards, samples, and rinse solutions used with a CE capillary should be filtered through a 0.45 µm or 0.2 µm membrane filter before use.

Filtering solutions helps:

• Minimize particulate contamination
• Reduce the risk of capillary blockage
• Improve run-to-run reproducibility
• Extend capillary service life

2. Rinse with Sodium Hydroxide Solution

After completing analyses, rinse the capillary with:  0.1 M Sodium Hydroxide (NaOH)

Recommended rinse time: 5 minutes

This step helps:

• Remove adsorbed sample components
• Eliminate residual buffer materials
• Regenerate the capillary surface
• Prepare the capillary for long-term storage

3. Flush with CE-Grade Water

Following the NaOH rinse, flush the capillary with:  CE-grade water or high-purity deionized water

Recommended rinse time: 5 minutes

This step removes any remaining NaOH and soluble residues that could affect future separations or damage the capillary during storage.

4. Dry the Capillary Before Storage

Whenever possible, gently purge the capillary using:

• Nitrogen gas
• Helium gas

Drying the internal lumen helps:

• Remove residual moisture
• Reduce contamination risks
• Minimize microbial growth
• Improve long-term storage stability

Benefits of Proper CE Capillary Storage

Following these storage procedures can help:

• Extend capillary lifespan
• Maintain consistent electroosmotic flow (EOF)
• Reduce capillary fouling
• Improve separation reproducibility
• Minimize downtime between analyses
• Preserve analytical performance

Additional Considerations

Capillary performance is often affected more by handling and maintenance practices than by age alone. Proper filtration of all solutions, routine cleaning, and careful storage can significantly improve the reliability and longevity of CE capillaries used in analytical, pharmaceutical, environmental, and research laboratories.

For laboratories performing routine CE analyses, implementing standardized capillary cleaning and storage procedures can help reduce troubleshooting and improve method consistency over time.