Method for the accelerated measurement of electroosmosis in chemically modified tubes for capillary electrophoresis

A traditional neutral marker approach is combined with fast pressure-driven mobilization to achieve a method that provides accelerated electroosmosis measurements in capillary electrophoresis systems. A marker injection is made prior to and following timed high-voltage application. The marker-sandwiched electrolyte plug is then pressure-driven out of the capillary tube under closely controlled conditions, while the signal is monitored in the usual way. Substantial reduction in measurement time is achieved by allowing the marker to travel only a fraction of the effective length (the injection to detection distance) over a shorter period of time, compared to the traditional method where voltage is applied until the neutral marker shows up at the detector window. One simple equation was derived to express the electroosmotic mobility of the electrolyte (μ(eo)) in terms of common operational variables. The method is particularly useful for low-electroosmosis measurements in wall-modified capillary tubes. The scope and limitations of the method are discussed.