Use of charge-transfer complex formation for the spectrophotometric determination of nortriptyline

Three simple and selective methods are proposed for the determination of nortriptyline hydrochloride in bulk form and in tablets. The first two methods are based on the formation of charge-transfer complexes between the drug base as a n-donor and quinhydrone or p-chloranil as pi-acceptor. The products exhibit absorption maxima at 497 and 560 nm in acetonitrile for quinhydrone and p-chloranil, respectively. The third method is based on the interaction of N-alkylvinylamine formed from the condensation of the free secondary amine group and acetaldehyde with p-chloranil to give a vinylamino substituted quinone. The coloured product exhibits an absorption maximum at 650 nm in dioxane. All variables were studied to optimize reaction conditions. Beer's law was obeyed and the relative standard deviations were found to be less than 1.5%. The methods have been applied to the analysis of nortriptyline hydrochloride in the bulk drug and in tablets.