A New Potentiometric Sensor for the Determination of Desipramine Based on N-(1-Naphthyl)Ethylenediamine Dihydrochloride-Tetraphenyl Borate

A new fast and sensitive potentiometric sensor is introduced for the determination of desipramine. The membrane was prepared by incorporating of N-(1-naphthyl)ethylenediamine dihydrochloride with sodium tetraphenyl borate (as an ion-pair). In this study, different plasticized poly(vinyl chloride) (PVC) membranes with different compositions were tested to construct the potentiometric sensor. A membrane with an ion-pair:dioctylsebacate:PVC ratio of 8.2:61.7:30.1 was selected. This drug electrode showed excellent Nernstian response over the concentration range 1.0×10^-6 and 1.0×10^-2 M. The electrode exhibited good selectivity for desipramine ions with respect to alkali, alkaline earth and several pharmaceutical substances. The response time of the electrode was less than 5 s over the entire concentration range. The coated-wire electrode could be used for at least two months without any considerable divergence in their potential. The electrode is suitable for using in aqueous solution in a wide pH range of 3.5-7.4. The sensor was used as an indicator electrode in the titration of desipramine hydrochloride with sodium tetraphenylborate solution. The sensor was successfully applied to determine desipramine hydrochloride in pharmaceutical and plasma samples with satisfactory results. The drug electrode has also been used to study the interaction of bovine serum albumin (BSA) with desipramine in buffer solution (phosphate, pH 7). The saturated quantities of desipramine binding were 11.02, 6.04, and 1.22 mol/mol in 0.01, 0.02, and 0.1% of protein, respectively. The Hill equations were applied to obtain cooperative drug bindings to BSA at 25^°C .