Direct determination of ephedrine and norephedrine in human urine by capillary zone electrophoresis.

This paper describes a simple and fast method for the simultaneous determination of ephedrine and norephedrine in urine by capillary zone electrophoresis. Separation and determination of these stimulants in human urine was performed in 50 mM phosphate buffer at pH 9.5, modifying the electroosmotic flow with acetonitrile. The method allows direct determination of the stimulants in urine in concentrations lower than 20.0 micrograms/ml, and has a limit of determination of 2.6 +/- 0.2 micrograms/ml for ephedrine and 2.3 +/- 0.2 micrograms/ml for norephedrine in urine and may be applied for doping control.