Development of Two Simple Spectrophotometric Methods to Assay Phenylephrine-HCl as Pure Form And in Its Drug Forms

This work includes the development of two spectrophotometric methods which are sensitive, accurate, stable, and has good recovery for the determination of phenylephrine-HCl as free form and in the pharmaceutical preparations. In the method (A), phenylephrine is oxidized by potassium permanganate in a basic solution of sodium hydroxide and the bluish-green color of the resulting manganate (MnO 42- ) is measured at wavelength 610 nm, which is linearly proportional to the amount of phenylephrine-HCl. Method (B), is involved the oxidation of phenylephrine-HCl by using an excess amount of N-bromosuccinimide in an acidic medium of hydrochloric acid solution, the remaining (unreacted) amount of N-bromosuccinimide is used to bleach indigo carmine dye and the absorbance of the blue color of the remaining dye is measured at the wavelength of 610 nm. which is directly proportional to the concentration of phenylephrine-HCl. The molar absorptivity coefficients of methods (A) and (B) are estimated and equal to 1.5722×10 4 and 5.5191×10 4 L/mol.cm, respectively. Beer’s law of the both methods are linear in the concentration ranges 0.2–8.0 µg/mL (method A) and 0.2–3.5 µg/mL (method B). The relative standard deviation values of methods (A) and (B) are also found to be better than 0.0286 and 0.0114, respectively. The two proposed methods are applied to estimate phenylephrine-HCl in injection and drop.