Determination of ephedrine and pseudoephedrine in Herba Ephedrae and Maxing Shigan Tang by capillary zone electrophoresis / 中国中药杂志

ABSTRACT

<p><b>OBJECTIVE</b>To establish a method for the determination of ephedrine and pseudoephedrine in Herba Ephedrae and Maxing Shigan Tang by capillary zone electrophoresis.</p><p><b>METHOD</b>The conditions of the experiment were optimized with a fused-silica capillary of 60 cm x 50 microm (50 cm effective length) in a running buffer of 50 mmol x L(-1) borax-20 mmol x L(-1) threonine (pH 9.27) and an applied voltage of 15 kV (room temperature). Samples were introduced by hydrodynamic injections (10 cm x 20 s)and determined with on-column UV monitoring at 210 nm. Phenobarbital was chosen as the internal standard.</p><p><b>RESULT</b>Ephedrine and pseudoephedrine are separated successfully within 8 min. The linear responses covered the ranges from 21.3 to 213 mg x L(-1) (r = 0.9996) for ephedrine and from 8.4 to 84 mg x L(-1) (r = 0.9995) for pseudoephedrine. The detection limits (S/N = 3) of ephedrine and pseudoephedrine were shown to be 1.45 and 1.48 microg x mL(-1), respectively, The quantitation limits (S/N = 10) of ephedrine and pseudoephedrine were shown to be 4.81 and 4.93 mg x L(-1), respectively. The average recoveries for ephedrine and pseudoephedrine were 97.5% and 98.6% with RSD less than 5.0%.</p><p><b>CONCLUSION</b>The method is simple, rapid, cost-effective and precise with satisfactory results.</p>