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 9.4×10−6 to 1.0×10−1 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 ≥1.0×10−5 M. The electrode is durable and can be used over a period of 5 months with good reproducibility (∼1% 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.