Simultaneous HPLC determination of betamethasone sodium phosphate and betamethasone dipropionate in compound betamethasone injection

OBJECTIVE A reversed phase HPLC method was developed to determine the contents of betamethasone sodium phosphate and betamethasone dipopinate simultaneously in compound betamethasone injection.METHODS The analysis was carried on a column of Shim-Pack CLC-ODS (4.6 mm×150 mm) with a mobile phase of methanol-0.05 mol·L -1 potassium dihydrogen phosphate solution (gradient elution from 58∶42 to 75∶25 in 18 minutes),using fluoromethasone as the internal substance.The detection wavelength was at 254 nm.RESULTS The linear range was 0.03 664～0.3 664 mg·mL -1(r=1.000 0,n=6) for betamethasone sodium phosphate and 0.087～0.868 mg·mL -1 for betamethasone dipropionate (r=0.999 6,n=6).The average recoveries of betamethasone sodium phosphate and betamethasone dipropionate were 101.3% (RSD=1.3%,n=9) and 99.0% (RSD=1.3%,n=9),respectively.The reproducibilities of the method (RSD) were 0.31% and 0.14% (n=7),respectively.CONCLUSION This method is rapid,simple and accurate.