Providing Enhanced Migration Time Reproducibility with a High-Voltage-Compatible Flow Sensor for Capillary...

Area of Science:

• Analytical Chemistry
• Separation Science
• Instrumentation

Background:

• Analyte identification in capillary electrophoresis (CE) relies on migration time, influenced by electrophoretic mobility and electro-osmotic flow (EOF).
• Migration time accuracy is compromised by parasitic flow caused by temperature or pressure fluctuations during CE runs.

Purpose of the Study:

• To develop and present a high-voltage-compatible flow sensor for real-time monitoring of volumetric flow within a CE capillary.
• To enable compensation for flow instabilities and enhance the reproducibility of CE separations.

Main Methods:

• A novel high-voltage-compatible flow sensor was designed and integrated into a CE system.
• The sensor achieved volumetric flow monitoring with nanoliter per minute (nL/min) resolution.
• Electropherograms were re-expressed using electromigration velocity instead of migration time for data analysis.

Main Results:

• The flow sensor accurately measured volumetric flow inside the capillary during CE separations.
• Direct measurement of flow and time allowed for effective compensation of flow instabilities.
• Re-expressing electropherograms by electromigration velocity improved run-to-run reproducibility by up to 25-fold.

Conclusions:

• The developed flow sensor provides a critical tool for improving the reliability of CE.
• Compensating for flow variations through direct measurement significantly enhances the reproducibility of CE separations.
• Utilizing electromigration velocity offers a more robust method for data analysis in CE.