The 3
D 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
4.0–24 lg mL1 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
the degradation product over concentration ranges of 4.0–
32 lg mL1 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 (El-Saharty et al., 2002).