Verapamil All-Solid-State Sensor and its Application for the Analysis of Pharmaceutical Formulations

An all-solid-state polymeric membrane electrode (ASS-PME) has been constructed for the analysis of Verapamil (VP) which is a calcium channel blocker used in the management of angina, arrhythmia and hypertension. The PME element of the ASS-PME has been based on the application of an ion-pair sensing reagent and the results revealed the best sensing behavior to occur in the case of compositions of 6%wt VP-tetraphenyl borate (the sensing element), 62%wt dioctyl phthalate as the solvent mediator, 30%wt poly(vinyl chloride) and 2%wt of an ionic liquid. The ASS element, on the other hand, is made of a composite of graphite, multiwall carbon nanotubes (MWCNTs), and epoxy resin coated on a Cu wire. The response behavior of the ASS-PME device was found to be linear from 1.0×10-7 to 1.0×10-3 M, with a slope of 55.3±0.2 mV/decade and a detection limit of 7.0×10-8 M was reached under the optimal conditions. The device was also successfully used in the real sample analysis.