Spectrophotometric Determination of Reboxetine through Condensation and Diazo-Coupling Reactions

Abstract

In the present study, two simple, sensitive and reproducible visible spectrophotometric methods were developed for the determination of reboxetine in pure form and in pharmaceutical formulations. The methods involve acid hydrolysis of reboxetine methane sulphonate (Reboxetine as methane sulphonate) and the product obtained was used for the estimation. Out of the two methods developed in the laboratory, the first method involves the condensation reaction of hydrolysed reboxetine methane sulphonate with ethyl acetoacetate in sulphuric acid medium and the second method involves the diazocoupling reaction of hydrolysed reboxetine methane sulphonate with diazotized p-sulphanilic acid in alkaline medium. They have absorption maxima at 400 nm and 430 nm respectively and obey Beer’s law in the concentration ranges of 0.5 - 0.3 μgmL^-1 and 1.0 - 7.5 μgmL^-1 respectively. Results of analysis were validated statistically and by recovery studies. The apparent molar absorptivity values (∈_max) obtained are 7.549 x 10⁴ L mol^-1 cm^-11 and 2.656x10⁴ Lmol^-1cm^-1 respectively. Both these have correlation coefficient value of 0.9999. The proposed methods have good precision and accuracy.