Polymeric membrane ion-selective electrode for determination of bismuth (III) in pharmaceutical substances

A PVC-based membrane of tridecylmethylammonium chloride reveals a Nernstian potentiometric response (with slope of 55 mV/decade and a correlation coefficient of 0.99) for complex of bismuth (III) with ethylenediaminetetraacetate-anion [Bi(EDTA)](-) over a wide concentration range (1 x 10(-1) to 3 x 10(-5) mol/l). The potential of this electrode is independent of pH in the range of 4.0-11.0. It has a fast response time of about 30 s and was used for a period of 3 months with good reproducibility. The detection limit of this membrane electrode was 1 x 10(-5) M. This sensor exhibits a very good selectivity for [Bi(EDTA)] over a wide variety of complex metal ions with ethylenediaminetetraacetic acid. The proposed electrode has been used in the direct potentiometric monitoring of bismuth (III) in stomach anti-acids.