The Zero Flow™ CE capillary is made from a standard, bare fused silica capillary with the inner surface treated so that it will not produce electroosmotic flow.
The surface is covalently bonded with linear polyacrylamide (LPA). Since LPA does not have any ionizable groups it is considered “effectively neutral” with no positive or negative charge. Therefore detectable EOF is not observed when properly using this capillary, even when full current is applied across the field.
Polyacrylamide should not be confused with polyimide which is a coating on the outer surface of CE capillaries. This outer coating imparts structural integrity and rigidity to the capillary, which would break easily without it. It does not effect the EOF or separation.
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