Bismuth (III) PVC membrane ion selective electrodes based on two compounds: Acylhydrazone and thiosemicarbazone with 1,3,4-thiadiazole

Two Bi 3   + selective electrodes based on L1 and L2 incorporated into a polyvinylchloride (PVC) membrane have been developed. The ionophores L1 and L2 are 2-(5-amino-1,3,4-thiadiazol-2-ylthio)-N′-benzylidene acetohydrazone and 1-(2-(5-amino-1,3,4-thiadiazol-2-ylthio) acetyl)-4-benzoylthiosemicarbazone, respectively. These electrodes are composed of dioctylphtalate (DOP) as a plasticizer and sodium tetraphenylborate (NaTPB) as the lipophilic additive. The best performance was obtained with the membrane compositions of L1 (0.30): PVC (33.22): DOP (66.36): NaTPB (0.12) (%, w/w) and L2 (1.00): PVC (33.00): DOP (65.91): NaTPB (0.09) (%, w/w). Two membrane electrodes show Nernstian response slopes towards Bi 3   + (20.2 and 19.7   mV/decade, respectively) over the concentration range of 10 −   7 –10 −   3 and 10 −   7 –10 −   2   M, respectively. The effects of the pH and the possible interfering cations were investigated. Both electrodes have a response time of about 10   s, and they can work in a certain concentration aqueous ethanol solution. The prepared electrodes were used as an indicator electrode in potentiometric titration of Bi 3   + ions with EDTA. The membrane sensors were also applied to the determination of Bi 3   + content in compound bismuth aluminate tablets.