Novel Validated Potentiometric Methods for the Determination of Torasemide in Bulk Drug, in Formulations and in Plasma

Three novel techniques for the selective determination of torasemide (tos) inbulk powder, in formulations and in plasma were described. the three techniques were theconstruction and electrochemical response characteristics of novel poly (vinyl chloride)matrix membrane sensors for torasemide cation based on the use of the ion-associationcomplexes of this cation with tetraphenyl borate, phosphotungestic acid and ammoniumreineckate counter anions as ion exchange sites in a plasticized pvc matrix, either as ionselective membranes, microcoated wire or as microsized graphite selective sensors. all thesesensors were prepared and fully characterized in terms of composition, life span, usable phrange, response time and temperature. the electrodes were selectively applied for thepotentiometric determination of torasemide in pure form, pharmaceutical preparations and inplasma. these sensors showed near nernstian responses with slopes of 28.3, 28.9, 27.9, 28.0,30.0, 27.7, 28.5, 29.2 and 27.5 mv over the concentration ranges of 1.0×10-6-1.0×10-2 m forall sensors. the electrodes exhibit good selectivity for (tos) with respect to a large numberof inorganic cations, organic cations, sugars and amino acids. the proposed electrodes offerthe advantages of simplicity, accuracy and applicability to turbid and colored samples. thebehavior of the three sensors in presence of human plasma was also studied and reasonableresults were obtained. all the fabricated sensors were validated according to the internationalconference on harmonization (ich) guidelines and successfully applied for thedetermination of the studied drug in pure form, pharmaceutical preparations and in plasmawithout any interference.