Spectrophotometric Determination of Etilefrine, Ritodrine, Isoxsuprine and Salbutamol by Nitration and Subsequent Meisenheimer Complex Formation

Abstract
A simple and sensitive colorimetric method has been developed for the determination of four phenolic drugs, namely, etilefrine hydrochloride, ritodrine hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate. The method is, mainly, based on the nitration of the drug molecule followed by the subsequent formation of meisenheimer complex with a nucleophilic reagent (acetone) in alkaline medium. The experimental conditions leading to optimum chromogen intensity and stability were carefully studied and incorporated in the general procedure. Under the proposed conditions, the method was applicable over the concentration range of 4.8–16 μg ml−1 for the four drugs. The suggested method was further applied for the determination of the studied drugs in bulk and pharmaceutical dosage forms. The results of the analysis were found to agree statistically with those obtained with either the official or the referee methods. The procedure is characterized by its simplicity with accuracy and precision.