Author/Authors :
Heidari، Parisa نويسنده Phase Equilibria Research Laboratory, Department of Chemistry, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran , , Jalali، Shabnam نويسنده Phase Equilibria Research Laboratory, Department of Chemistry, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran , , Mofidi، Zahra نويسنده Phase Equilibria Research Laboratory, Department of Chemistry, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran , , Zamani، Abas ali نويسنده Environmental Science Research Laboratory, Department of Environmental Science, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran , , Yaftian، Mohammad Reza نويسنده Phase Equilibria Research Laboratory, Department of Chemistry, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran ,
Abstract :
Nitrobenzo18-crown-6 (NB18C6) has been examined as an ion sensing material
for fabricating a PVC membrane lead ion-selective potentiometric sensor. The best
performance of the electrode was observed with a membrane composition formed by 30%
PVC, 58.5% ortho-nitrophenyloctylether (NPOE) as plasticizing solvent mediator, 9% of
NB18C6 as ionophore and 2.5% sodium tetraphenylborate (NaTPB) as ion excluder. The
electrode presents a nearly Nernstian response (a slope of 30.5±0.5 mV/decade) over a
concentration range 1×10-5-1×10-2 M of lead ions, with a limit of detection 8.9×10-6 M. Its
potential response was independent on the pH variation in the range 2.2-4.1. The dynamic
response time of the electrode to achieve a steady potential was relatively fast and was found
to be about 6 seconds. The selectivity of the prepared electrode relative to some mono-, di-,
tri- and tetra-valent metal ions was examined. This electrode can be used for 3 months
without considerable divergences in the potential response. It was successfully used as an
indicator electrode for the complex formation titration of lead solutions by EDTA.
