Validated Selective HPLC–DAD Method for the Simultaneous Determination of Diclofenac Sodium and Lidocaine Hydrochloride in Presence of Four of Their Related Substances and Potential Impurities


This study presents a selective high-performance liquid chromatography (HPLC) with diode array detection (DAD) method for the simultaneous estimation of diclofenac sodium and lidocaine hydrochloride in presence of four of their related substances and potential impurities, namely, 2,6-dimethylaniline (DMA), 2,6-dichloroaniline (DCA), N-phenyl-2,6-dichloroaniline (PDCA), and N-chloroacetyl-N-phenyl-2,6-dichloroaniline (CPDCA). Some of these related substances are reported as degradation products as well. Effective chromatographic separation was achieved using Waters Symmetry C18 column, (3.9 × 150 mm, 5 μm particle size) with gradient elution of the mobile phase composed of 0.05 M orthophosphoric acid and acetonitrile. The gradient elution started with 5% (by volume) acetonitrile, ramped up linearly to 65% in 5 min then kept constant till the end of the run. The mobile phase was pumped at a flow rate of 1.5 mL min−1. The multiple wavelength detector was set at 220 nm, and quantification of both drugs was based on measuring their peak areas. The retention times for lidocaine and diclofenac were about 5.5 and 9.5 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 10–200 μg mL−1 for both drugs with correlation coefficients not less than 0.9998. The proposed method proved to be selective by resolution of the two drugs from their related substances and potential impurities. The validated HPLC method was successfully applied to the analysis of this binary mixture in the combined formulation (ampoules dosage form), and the assay results were favorably compared with a previously reported HPLC method. The proposed method made use of DAD as a tool for peak identity and purity confirmation.





Journal/Conference Information

Acta Chromatographica ,27(2015)3, 477–493