Determination of bismuth(III) by direct potentiometry and potentiometric titration, with an electrode sensitive to Bi(3+)

A liquid-state ion-exchange electrode containing the chelate bismuth(III) complex with 5-mercapto-3-(naphthyl-2)-1,3,4-thiadiazole-2-thione in tetrachloroethane is applied to the determination of bismuth(III) by direct potentiometry and potentiometric titration. The influence of various interfering cations is discussed. In the presence of potassium cyanide as masking agent, Ni(II), Co(II), Cu(II), Ag(I) and Hg(II) do not interfere in the potentiometric EDTA titration. Satisfactory results have been obtained for the determination of bismuth(III) in Wood's metal and two pharmaceuticals.