Development of Novel Plastic Membrane Ion- Selective Electrode for Metformin Hydrochloride

A new plastic membrane ion-selective electrode for determination of metformin hydrochloride has been prepared, after forming the ion pair of metformin hydrochloride with sodium tetraphenylborate. Dioctyl phthalate and sodium tetraphenylborate were used as plasticizer and counter ion respectively. The electrode exhibited a linear potential response in the concentration range 1 × 10 M–1 × 10 M with slope of 42.0±0.82 mv per ecade. The electrode has a rapid response time (45 s), shorter conditioning time (2 h) and a lower limit of detection (1 × 10 M). The electrode showed high selectivity for metformin hydrochloride with respect to some common ions, excipients and other drugs present as combined dosage formulations. Stability studies of ion-selective membrane were carried out by differential scanning calorimetry. The electrode can successfully be applied for the analysis of metformin hydrochloride in pure solution, pharmaceutical preparations, biological fluid and in presence of its degraded products.