Overview

This troubleshooting post explains why Zero‑Flow™ CE capillaries typically show no buffer elution, even at high voltage. Their covalently bonded inner coating eliminates surface hydroxyl activity, preventing electroosmotic flow (EOF) and ensuring that ions move solely by electrophoretic mobility. This design improves robustness by avoiding uncontrolled EOF, a common source of variability in CE. Buffer will only exit the capillary when external pressure is applied.If buffer still does not flow under pressure, the capillary may be blocked and should be evaluated by customer service.

Understanding these behaviors helps prevent misdiagnosis of normal characteristics as product defects.

Buffer Is Not Eluting from a Zero‑Flow Capillary — Is the Capillary Defective?

Zero‑Flow™ Capillaries supplied by MICROSOLV are designed to operate with no electroosmotic flow (EOF). The covalently bonded inner coating eliminates the surface hydroxyl activity that normally generates bulk flow in CE.

Because of this, it is normal to observe no buffer elution—even at high voltages. This lack of EOF is intentional and beneficial, since uncontrolled EOF is a known source of poor robustness and variability in CE separations.

When Should Buffer Come Out?

During conditioning, pressure may be applied to push buffer through the capillary. In this case, you should see buffer exiting the outlet.

• If buffer flows under pressure → the capillary is functioning normally.

• If buffer does not flow under pressure → a blockage is likely.
  Please contact MICROSOLV Customer Service at customers@mtc‑usa.com 

Analyte Movement

In Zero‑Flow capillaries, both cationic and anionic analytes move solely due to their electrophoretic mobility, not EOF.

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