Continuous capillary electrophoresis with flow injection and its application for determination of Ephedrine and pseudo-ephedrine in Chinese medicinal preparations

This article presents a new, simple and rapid continuous separation method by combination of flow injection with capillary electrophoresis designed for the analysis of basic traditional Chinese medicines. The device was produced using commercial capillary and components readily available in analytical laboratory. In double-T configuration, the designed horizontal separation channel was 25 mum i.d. x 146 mm length (an effective separation length of 93 mm) quartz capillary, with two vertical elicitation arms produced from 0.5 mm i.d. pump tubing. The capillary was embedded in a 40 x 20 x 3 min organic glass base. Using the double-T configuration, continuous introduction of a series of samples was achieved. More than 3.00 resolution for ephedrine and pseudo-ephedrine were obtained using 100 mM borate buffer (pH 9.80) within 8 min in 25 mum separation channel with an electrical field strength of 137 V/cm (UV detection at 215 nm). The linear calibration range was 50-1500 mug/mL (ephedrine, r=0.9982; pseudo-ephedrine, r=0.9990) for both analytes. The limits of detection were 2.65 mug/mL for ephedrine and 2.92 mug/mL for pseudo-ephedrine. In this device, the contents of ephedrine and pseudo-ephedrine in five Chinese medicinal preparations were determined with RSDs (n=5) in range 1.16-4.51% and recoveries in range 90.4-114.6%. Copyright (C) 2004 John Wiley Sons, Ltd.