RESUMEN
Chemometric spectrophotometry and HPLC were applied to the simultaneous determination of the two non-steroidal anti-inflammatory drugs; diflunisal [I] and naproxen [II]. The applied chemometric techniques are multivariate methods including classical least squares [CLS], principal component regression [PCR] and partial least squares [PLS]; and the second derivative of the ratio spectra [2Dr] method. To develop the multivariate methods, the UV absorption spectra of the standard solutions of the training and validation sets in methanol were recorded in the range of 242-274 nm at 2 nm intervals. The specificity of the studied multivariate methods has been tested. In the 2Dr method, analytical signals at 235 and 259 nm were selected for the determination of [I] and [II], respectively. The HPLC method depends on reversed-phase separation using C18 column. The mobile phase consists of a mixture of acetonitrile - acetate buffer [pH 4.2; 50 mM] [60:40, v/v]. The UV detector was set at 255 nm. The developed methods were validated and successfully applied to the simultaneous determination of [I] and [II] in their tablets. The assay results obtained using the chemometric methods were statistically compared to those of the HPLC method and good agreement was observed