Extractive spectrophotometric determination of some skeletal muscle relaxant drugs through ion-pair formation with molybdenum [V] and thiocyanate

ABSTRACT

A spectrophotometric procedure was developed for the determination of orphenadrine citrate [I], tizanidine hydrochloride [II] and pancuronium bromide [III]. The method was based on ion-pair complex formation with molybdenum [V] thiocyanate complex in an acidic medium. Dichloromethane was used for the extraction of the orange red ion-pair and its absorbance was measured at 470 nm. The molar absorptivities were 1.34 x 104, 1.19 x 104 and 4.35 x 104 1 mol-1 cm-1 for I, II and III, respectively. The ion-pair was stable for more than one day at room temperature. The proposed method was applied successfully for the analysis of samples in bulk powder and in dosage forms with recoveries in the range of 99-101%, 99.8-101.4% and 98.9-101.2%, respectively