Determination of relevant substances of diclofenac diethylamine emulgel by HPLC

Objective To establish an HPLC method for the determination of relevant substances of diclofenac diethylamine emulgel. Methods An Utimate C18 column was used with the mobile phase of 0.2% acetic acid(pH=3.0)-methanol(34∶66).The detection wavelength was 254 nm. Results Blank adjuvant didn't interfere with the detection of impurities.The relevant substances were separated from diclofenac diethylamine,and the detection limit was 0.02 μg·mL-1.When the absorption coefficient of the impurities was equal to or greater than that of diclofenac diethylamine,the minimum detectable quantity of impurities was 0.002%. Conclusion The method is simple and sensitive,which is suitable for the determination of relevant substances of diclofenac diethylamine emulgel.