Indirect Spectrophotometric Determination of Phenylephrine Hydrochloride in Pharmaceutical Preparations

Abstract

A simple and sensitive spectrophotometric method was developed for determination of phenylephrine-HCl in pharmaceutical preparations . The procedure is based on the oxidation of phenylephrine-HCl with Fe (III) in acidic medium to produce Fe (II), then reaction of Fe(II) with 2,2'-bipyridyl to produce a red complex which is water-soluble, stable, and has a maximum absorption at 523 nm against the reagent blank with a molar absorptivity of 7.1295×104 l.mol-1.cm-1.The variables affecting the intensity of complex were studied and optimized. Under the optimum conditions, the calibration graph was linear over the range 2.5-80 μg phenylephrine-HCl/25 ml (0.1-3.2ppm), with a relative error of +0.79 to +0.82% and a relative standard deviation of ±3.44 to ±3.57% depending on concentration level. The proposed method was applied to the determination of phenylephrine-HCl in two pharmaceutical preparations (nose drop and syrup) . The amount of phenylephrine-HCl found is very similar to that obtained by a standard method.