Two simple, accurate and sensitive methods had been developed and validated for determination of loxoprofen (LOXO) in pure and dosage forms. The first method is based on the formation of ion-associate complexes between the drug and arsenazo I (ARS I) or Bromophenol blue (BPB) to give colored products maximally absorbed at 535 and 640 nm with the two reagents, respectively. Different factors affecting the reaction between the drug and the two reagents were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9993 and 0.9988) were found between absorbance and concentrations of the drug in the concentration range 2.70-91.4 and 2.8-107.3 µgml-1 for the two reagents, respectively. The assay limits of detection and quantification were 1.57 and 1.11 µgml-1, 2.51 and 2.32 µgml-1, respectively. In the second method, first derivative spectrophotometry was used where it was found that LOXO can be determined by measuring the amplitude at 232 nm. The methods were validated, in terms of accuracy and precision and the results were satisfactory. The proposed methods were successfully applied to determination of the investigated drug in pure and pharmaceutical dosage forms without interference from the common excipients. The results obtained by the proposed methods were comparable with those obtained by reference methods |
