Spectrophotometric Determination of Salbutamol Via Oxidative Coupling Reaction Using Reagent Benzidine

Abstract

A simple, sensitive and rapid spectrophotometric method has been developed for the determination of salbutamol (SAL) by oxidative coupling reaction of salbutamol with the reagent benzidine in the potassium periodate as oxidizing agent in alkaline medium forming a pink colour. The product gave maximum absorption at 333.5 and 509 nm. The molar absorptivity is 26059.77 and 2297.28 l/mol.cm at 333.5 and 509 respectively. For concentrations obeyed Beer's law in the range 0.2-16 µg.ml-1. The recovery was 101.9% and 102.2% with relative standard deviation < 3.0 % for salbutamol. Salbutamol and benzidine products were formed in the ratio of 1:2 (reagent: drug). The stability constant of the products were5.19×1012 l2.mol-2 and 1.13×1012 l2.mol-2 at first and second wavelength respectively indicating a good stability for the product. There is no interference was observed from common excipients present in pharmaceutical preparations. The suggested method was successfully applied to determine salbutamol in pharmaceutical preparation (tablet).