REAL-TIME MEASUREMENT OF ELECTROOSMOTIC FLOW IN CAPILLARY ZONE ELECTROPHORESIS

A method is developed for measuring the electroosmotic (bulk) flow rate continuously in capillary zone electrophoretic separations, which is based on introducing a reference flow of solution containing a fluorescent marker into the running buffer downstream from the detection zone. This technique can determine changes as small as 1% in the flow rate during a separation. The response time of the measurement is similar to 1 s, and the dynamic range extends over more than an order of magnitude in flow rate. This method is able to correct for changes (run to run) in the migration times of analytes that are caused by alteration of the capillary surface during analysis of complex samples, such as human serum. In addition, this method makes more practical the use of adjusted migration indices for the general representation of migration data and enhances the accuracy and precision of analyses in capillary zone electrokinetic separations.