Assay of bismuth in combined medicinal formulations using an ion-selective electrode

An ion-selective electrode (ISE) with a plasticized membrane reversible to the ethylenediaminetetraacetic bismuthate (III) anion ([Bi(EDTA)] − ) is described and a method for the direct potentiometric estimation of bismuth (III) in antacid formulations is presented. The active group of the ion exchanger for the [Bi(EDTA)] − anion-reversible ISE was the tridodecylmethylammonium cation.