RESUMEN
Objective To establish an HPLC method for determination of ephedrine hydrochloride and pseudoephedrine hydrochloride in Maxing oral solution .Methods Phenomenex Hydro-RP (250 mm × 4 .6 mm ,4 μm) was adopted .Acetonit-nile (A) and 0 .1% phosphonic acid solution (0 .1% triethanolamine solution)(B) was used as gradient mobile phase(0-20 min , 3% →10% A)at flow rate was 1 .0 ml/min and the program of UV gradient absorbance detection was 210 nm .The sample vol-ume was 20 μl .Results A good linearity was obtained over the concentration range of 0 .99-39 .6 μg/ml for ephedrine hydro-chloride (r=0 .999 9) and 1 .09-43 .6 μg/ml for pseudoephedrine hydrochloride (r=0 .999 9) .The average recovery of ephed-rine hydrochloride was 101 .5% with RSD of 1 .77% (n=6) ,and the average recovery of pseudoephedrine hydrochloride was 100 .8% with RSD of 1 .96% (n=6) .Conclusion This method was simple ,accurate and quick ,which could be used for deter-mination and quality control of Maxing oral solution with good selectivity and repeatability .