Simultaneous determination of the two non-steroidal anti-inflammatory drugs; Diflunisal and Naproxen in their tablets by chemometric spectrophotometry and HPLC

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

Chemometric determination of rabeprazole sodium in presence of its acid induced degradation products using spectrophotometry, polarography and anodic voltammetry at a glassy carbon electrode

Chemometric stability indicating methods are presented for the determination of rabeprazole sodium in presence of its acid induced degradation products using spectrophotometry, differential pulse polarography and differential pulse anodic voltammetry at a glassy carbon electrode. The applied chemometric techniques are multivariate ones including classical least squares [CLS], principal component regression [PCR] and partial least squares [PLS]. A difference spectrophotometric [?A] method has also been applied. To develop the multivariate calibrations, a training set was used, consisting of 20 mixture solutions of rabeprazole sodium and its degradation products. These mixtures show percentage degradation ranging from 0.5-65%, 0.5-95% and 0.6- 75% for the spectrophotometric, polarographic and anodic voltammetric calibrations, respectively. The UV absorbances were recorded in 0.1 M NaOH within the wavelength range 220-340 nm at 2 nm intervals. The polarograms and anodic voltammograms were recorded in Britton- Robinson buffer [pH 8.0] within the potential range -500 to -1508 and 400 to 1192 mV at 6 mV intervals with a pulse amplitude of -100 and 50 mV, sweep rate of 15 and 10 mV s-1 and pulse interval of 0.4 and 0.6 s for the polarographic and anodic voltammetric methods, respectively. All the studied methods have been validated and successfully applied to the determination of rabeprazole sodium in tablet dosage form. The results were statistically compared to those obtained using a published HPLC method. No significant difference has been found