Poly(vinyl chloride) ion-selective electrodes for piribedil determination

Piribedil (PD) ion-selective electrodes have been constructed from poly(vinyl chloride) matrix membrane containing piribedil-tetraphenylborate (PD-TPB) as the electroactive component with dibutylphthalate or dioctylphthalate as the plasticizing solvent mediator. The electrodes displayed a linear response over the concentration range 2.0 x 10(-5) to 10(-2) M PD. The working pH ranges of the electrodes were 3.5-6.4 and 3.0-6.0, and the isothermal coefficients of the cells were 0.00129 and 0.00096 V/degrees C respectively. The electrodes were used for the determination of the diprotonated PD species, the most successful being that based on dioctylphthalate solvent mediator. The electrodes show a linear response over the concentration range of 8.0 x 10(-6) to 10(-2) M PD, with Nernstain slope 30 mV/PD concentration decade when preconditioned by soaking in distilled water for 30 min. The electrodes exhibit good selectivity for the PD with respect to a large number of inorganic cations and organic substances of biological fluids. Piribedil is determined successfully in pure solutions and in tablets or in biological fluids using the standard additions and potentiometric titration methods. The membrane withstood soaking in distilled water for more than 5 months.