Overview
This post explains how flow rates are defined and expressed in Controlled‑Flow CE capillaries. The terms High, Medium, and Low Flow represent relative electroosmotic flow strengths, not absolute values, and are based on comparison to a bare fused silica capillary under identical conditions. Because the Controlled‑Flow coating slows the electroosmotic flow, each flow category produces characteristic migration times. Example data for a neutral marker demonstrates the relative speeds of the three Controlled‑Flow types versus bare fused silica, helping users choose the correct flow rate for their separation needs.
Flow Rates in Controlled‑Flow CE Capillaries Explained
The flow terms used for Controlled‑Flow CE capillaries—High, Medium, and Low Flow—are nominal designations that describe relative flow behavior compared with bare fused silica capillaries.
All Controlled‑Flow capillaries will run slower than bare fused silica because of the internal bonded coating. However, within the Controlled‑Flow family, the relative flow order is:
- High Flow → fastest
- Medium Flow → intermediate
- Low Flow → slowest
For example, under a set of conditions where a neutral marker produces a migration time of 3.2 minutes on a bare fused silica capillary, the same marker will migrate in approximately:
- 4.3 minutes using a High Flow Controlled‑Flow capillary
- 6.5 minutes using a Medium Flow capillary
- 8.2 minutes using a Low Flow capillary
These predictable differences make it easier to choose the appropriate flow type based on the needs of your CE method.
Click HERE to view ordering information for Zero‑Flow and Controlled‑Flow CE capillaries.