Abstract: Objective To confirm the content determination method of urapidil in raw materials more scientifically and reasonably. Methods Mettler DL-55 potentiometric titration was used to titrate the content of urapidil by perchloric acid. Acetic acid and acetic anhydride were used as solvent. HPLC method was performed on a Syncronis C18 column (100 mm×2.1 mm,1.7 μm). The mobile phase was acetonitrile-0.05 mol·L-1 NaH2PO4 (20:80) with the flowing rate of 1.0 mL·min-1. The detection wavelength was set at 268 nm and the column temperature at 35℃. Results The average recovery rate of potentiometry titration was 99.98% and RSD was 0.41% (n=3). The average recovery rate of HPLC was 100.93% and RSD was 0.60% (n=3). The results of potentiometry titration and HPLC had significant statistic difference, and the recovery rate of potentiometry titration was closer to 100%. Conclusion Potentiometry titration could avoid the error due to the standard substance. The method is simple, fast, accurate and can be used to determine the content of urapidil.

Key words: urapidil, content determination, potentiometry titration, HPLC