Novel Polymeric Membrane and Coated Wire Electrodes for Determination of Alverine Citrate in Pharmaceutical Formulations and Biological Fluids

Selective and sensitive alverine electrodes have been fabricated by constructing a polymeric membrane (PME) and coated wire (CWE) electrodes. These are based on the ion-pair between phosphotungstic acid (PME1, CWE1) and phosphomolybdic acid (PME2, CWE2) in a poly (vinyl chloride) matrix, plasticized with DBP. The influence of membrane composition and pH on the potentiometric responses of electrodes was investigated. The response characteristics of the membrane were compared with polymeric membrane electrode (PME) as well as with coated wire electrode (CWE). The electrodes exhibit Nernstian slope of 59.1 +/- 0.4, 59.3 +/- 0.6, 59.2 +/- 1.1 and 59.5 +/- 1.1 mV decade(-1) with limits of detection of 7.6x10(-6), 8.3x10(-6), 6.6x10(-6) and 8.1x10(-6) mol L-1 alverine citrate for PME1, PME2, CWE1 and CWE2, respectively. Furthermore, the electrodes generated constant potentials in the pH range of 1.44-8.05 and 1.42-8.31 for PME1 and PME2, respectively. Selectivity coefficients for alverine citrate relative to numbers of potential interfering substances were investigated. The electrodes were highly selective for alverine over a large number of similar compounds. The proposed electrodes displayed useful analytical characteristics for the determination of alverine citrate in bulk powder, pharmaceutical formulation, and biological fluids (urine and plasma). The practical utility of the proposed electrodes has also been demonstrated by thier usage as indicator electrodes in potentiometric titration of phosphotungstic acid with alverine cation solution.