Magnesium-tetrazaporphyrin incorporated PVC matrix as a new material for fabrication of Mg2+ selective potentiometric sensor

Membrane incorporating [Mg{(TAP)(SBn)(8)}] complex, (I), as ionophore with composition I:NaTPB:DOP:PVC in the ratio 10:2:133:200 (w/w) exhibits the best result for potentiometric sensing of Mg2+ ions. This gives linear potential response in the concentration range of 9.4 x 10(-6) to 1.0 x 10(-1) M with a slope of 29.2 +/- 0.4 mV per decade of activity of Mg2+. Standard deviation in observed values of potentials in this concentration range, from the least square fit line, found to be 2.91 mV with 90% confidence limit lying within +/-0.4 mV per decade of activity. The electrode works satisfactorily in the pH range 3.5-7.8 and shows a fast response time of 13 +/- 2 s. It shows good selectivity for Mg2+ over other mono-, bi- and tri-valent cations. Only K+ and Zn2+ cause slight interference if present at concentrations greater than or equal to 1.0 x 10(-5) M. The electrode is durable and can be used over a period of 5 months with good reproducibility (similar to1% error). It has been successfully used as an indicator electrode in potentiometric titration of Mg2+ against EDTA as well as for the determination of Mg2+ in simulated mixtures. (C) 2004 Elsevier B.V. All rights reserved.