pH-Induced Difference Spectrophotometric Methods for the Determination of Oxyphenbutazone in Some Pharmaceutical Formulations

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Abstract
Two pH- induced difference- spectrophotometric procedures for the determination of oxyphenbutazone in pharmaceutical formulations are reported. Both procedures depend upon the sensitivity of the ultraviolet spectrum of oxyphenbutazone towards the pH of the solvent medium. In one procedure, the absorbance difference of oxyphenbutazone in an acid solvent (0.01 NHCl) and in an alkaline one (0.01 N NaOH) is measured at 254 nm; the mean percentage recovery amounts to 100.2±1.23 (p=0.05). The second procedure depends upon measurement of the absorbance difference of the drug in the acid solvent then in a pH 7-phosphate buffer at 262 nm; the mean percentage recovery amounts to 100.1±1.03 (p=0.05). The possible sources of interference in pharmaceutical formulations are studied and the two procedures are adapted to the analysis of some market preparations collected at random.