Spectrophotometric Determination of Etilefrine Hydrochloride, Prenalterol Hydrochloride and Ritodrine Hydrochloride in pharmaceutical dosage form Through Nitrosation and Subsequent Copper Chelation

Abstract

Abstract A colorimetric method is proposed for the determination of etilefrine hydrochloride, prenalterol hydrochloride and ritodrine hydrochloride, and their dosage forms. The proposed method depends on nitrosation of the phenolic drugs with sodium nitrite in acidic medium with subsequent chelation by copper (II) ions resulted in the formation of stable red color copper chelate which shows a maximum absorbance at 510, 460 and 520 nm for etilefrine, prenalterol and ritodrine chelate, respectively. The experimental conditions leading to optimum color stability and intensity were studied. The proportions of the reactants and the stability constant for the copper chelates were determined. The copper chelates obey Beer's law and their absorbance were used for the determination of the three drugs in their pharmaceutical dosage forms. To confirm the validity of the proposed method, recovery studies were carried out using the standard addition method. At the same time, the results of the applications of the method to the assay of the tested drugs in their commercial preparations were compared statistically with either an official or a published method. The proposed method demonstrate high percentage of recoveries with good accuracy and precision.