Validation of an HPLC Method for the Determination of Diclofenac Diethylamine and Three of Its Impurities in a Gel Pharmaceutical Form

Abstract Background Monitoring impurities in drug products is a principal requirement of pharmaceutical regulatory authorities all over the world to ensure drug safety. For this reason, there is a great need for analytical QC of dugs products. Objective In this study, a simple, efficient, and direct HPLC method was developed for the determination of three impurities of diclofenac. Methods The HPLC method was developed using a mobile phase which consisted of an HPLC grade mixture, acetonitrile–0.01M phosphoric acid adjusted to pH 2.3 (1 + 3, by volume). Results The separation was performed in 15 min. The calibration curves of the three impurities were linear; the correlation coefficients were 0.999 at concentrations of 0.00015–0.003 µg/mL. Conclusion The validation of this method shows that it meets all validation criteria. This shows the reliability of this method for the routine control of diclofenac impurities. Highlights The validation of a robust HPLC method for the determination of diclofenac impurities is of great importance for the pharmaceutical industry to control its products.