Stability-indicating spectrophotometric and densitometric methods for determination of aceclofenac

Three methods were developed for the determination of aceclofenac in the presence of its degradation product, diclofenac. In the first method, third-derivative spectrophotometry (D3) is used. The D3 absorbance is measured at 283 nm where its hydrolytic degradation product diclofenac does not interfere. The suggested method shows a linear relationship in the range of 4-24 micrograms mL-1 with mean percentage accuracy of 100.05 +/- 0.88. This method determines the intact drug in the presence of up to 70% degradation product with mean percentage recovery of 100.42 +/- 0.94. The second method depends on ratio-spectra first-derivative (RSD1) spectrophotometry at 252 nm for aceclofenac and at 248 nm for determination of degradation product over concentration ranges of 4-32 micrograms mL-1 for both aceclofenac and diclofenac with mean percentage accuracy of 99.81 +/- 0.84 and 100.19 +/- 0.72 for pure drugs and 100.17 +/- 0.94 and 99.73 +/- 0.74 for laboratory-prepared mixtures, respectively. The third method depends on the quantitative evaluation of thin-layer chromatography of aceclofenac using chloroform:methanol: ammonia (48:11.5:0.5 v/v/v) as a mobile phase. Chromatograms were scanned at 274 and 283 nm for aceclofenac and diclofenac, respectively. The method determined aceclofenac and diclofenac in concentration ranges of 2-10 and 1-9 micrograms spot-1 with mean percentage accuracy of 100.20 +/- 1.03 and 100.14 +/- 0.98 for pure drugs and 99.77 +/- 0.74 and 100.07 +/- 0.78 for laboratory-prepared mixtures, respectively. This method retains its accuracy in the presence of up to 80% degradation product for the studied drug. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparation. The validity of the proposed methods was further assessed by applying a standard addition technique. The obtained results agreed statistically with those obtained by the reported method.