Spectrophotometric Methods for Resolving Ternary Mixture of Diflunisal, Naproxen and Diflunisal Toxic Impurity

Abstract

Two spectrophotometric methods have been investigated for determination of Diflunisal (DIF), Naproxen (NAP) and Diflunisal toxic impurity; Biphenyl-4-ol (BIP). Method (I) is modified ratio difference spectrophotometric method. This method can determine DIF and NAP in presence of BIP. In this method DIF has been determined by measuring the difference of amplitudes values between 250.2 and 260.4 nm in the obtained ratio spectra (using standard spectrum of 3 μg/mL of NAP as a divisor) while NAP has been determined using the difference between 216.8 and 239.8 nm (using standard spectrum of 1 μg/mL DIF as a divisor). Method (II) is multivariate calibration models including principal component regression (PCR) and partial least square (PLS), using wavelength range of 200-350 nm for both models. Regarding to the preprocessing state, non-scale was applied for PCR model while mean center of data for PLS one. The developed models were successfully applied to predict the concentration of studied components in validation set and good results were obtained. The developed methods have been successfully applied for resolving the three studied components in their ternary laboratory prepared mixtures. Also they have been used for measuring DIF and NAP in their pharmaceutical dosage form where good results were obtained.