Immobilization of N',N'',N''' tris(2-pyridyloxymethyl) ethane as a neutral carrier in a PVC-membrane medium for lead(II) ion-selective electrodes
Pawan Kumar, Susheel Mittal, Ashok Kumar S. K.
School of Chemistry & Biochemistry Thapar University Patiala
In the present work, N',N'',N''' tris(2-pyridyloxymethyl) ethane (TPOME) has been used as an ionophore in a PVC based membrane. To explore the binding efficiency of TPOME towards various metal ions, UV-visible spectroscopic technique was applied. The membrane electrode with a composition 33: 5: 62: 3 (PVC :TPOME: o-NPOE : NaTPB) exhibits Nernstian response towards Pb(II) ions with a slope 30mV/decade, over a concentration range of 1x10-5 M to 1x10-1 M. The potential response remains almost unchanged over pH range 3.7-6.4. The electrode shows fast response time of 15±2 seconds and a life time of four months. It shows good selectivity for Pb (II) ions over other mono-, di- and trivalent cations. The electrode response is satisfactory in mixed solvent media up to 30% (v/v) non-aqueous contents. Selectivity of the ionophore for Pb(II) ions was determined byspectrophotometeric method. The electrode can also be used as an indicator electrode in the potentiometric titration of Pb(II) ions with standard chromate solution and its determination in real life samples. Surface morphology of membrane electrode at different stages of its development and use is also discussed and comparison of proposed electrodes is done with the reported electrodes.
Keywords: PVC, neutral carrier, Ionophore, liquid membrane. Lead ions, selectivity coefficients, Nernstian response.