Neutral Carrier-Based Zinc-Selective Electrode

A new PVC based liquid membrane containing N,N,N',N'-Tetrakis(2-pyridylmethyl) ethylenediamine (I) as an ionophore has been developed as zinc ion-selective electrode. The best performance was observed with an electrode composition (w/w); PVC (33%), 2-nitro phenyloctylether (60%), ionophore (I) (5%) and sodium tetrakis(4-chlorophenyl) borate as lipophilic salt (NaTpCIPB, 2%). The electrode shows a linear dynamic response in the concentration range 5.0 x 10(-6) M to 1.0 x 10(-1) M with a Nernstian slope of 30 mV/decade and a detection limit as 1 x 10(-6) M. It has a response time of 20 seconds and can be used for at least 4 months without any significant divergence in potentials. The proposed sensor shows good selectivity with respect to alkali, alkaline earth and transition metal ions. It can be used in the pH range 3.0-8.0 and electrode has been used as an indicator electrode in potentiometric titrations of zinc(II) ions with Na2S. The electrode also has been applied successfully for the determination of zinc ions in real life samples.