Magnesium-tetrazaporphyrin incorporated PVC matrix as a new material for fabrication of Mg(2+) 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 Mg(2+) ions. This gives linear potential response in the concentration range of 9.4x10(-6) to 1.0x10(-1)M with a slope of 29.2+/-0.4mV per decade of activity of Mg(2+). Standard deviation in observed values of potentials in this concentration range, from the least square fit line, found to be 2.91mV with 90% confidence limit lying within +/-0.4mV per decade of activity. The electrode works satisfactorily in the pH range 3.5-7.8 and shows a fast response time of 13+/-2s. It shows good selectivity for Mg(2+) over other mono-, bi- and tri-valent cations. Only K(+) and Zn(2+) cause slight interference if present at concentrations >/=1.0x10(-5)M. The electrode is durable and can be used over a period of 5 months with good reproducibility ( approximately 1% error). It has been successfully used as an indicator electrode in potentiometric titration of Mg(2+) against EDTA as well as for the determination of Mg(2+) in simulated mixtures.
Gupta
V K
VK
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667, India.
Prasad
Rajendra
R
Kumar
Azad
A