Fe (II) Ion-Selective Membrane Electrode based onTetra-Phenyl Porphyrin in PVC Matrix

Abstract

Fe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrix<br />membrane containing neutral carrier tetra phenyl porphyrin (TPP) ionophore. The addition of<br />sodium tetraphenylborate (NaTPB) and the plasticizer DBP has been found to substantially<br />improve the performance of the sensor. The best performance was obtained with the sensor having<br />a membrane of composition of TPP: NaTPB: DBP: PVC in the ratio 6:3:61:30 respectively. The<br />sensor shows a linear response over a wide concentration range of 1.0 x 10-6 to 1.0 x 10-2 M with<br />a Nemstian slope of 29.4 ± 0.6 mV decade-1 and a detection limit of 9.6 x 10-7 M. It has a<br />response time of <12 s and can be used for more than seven weeks without any measurable<br />divergences in its potentials. The proposed sensor could be used in a pH range of 3.0-5.0.<br />Potentiometric selectivity coefficients determined by matched potential method (MPM) indicate<br />excellent selectivity for Fe2+ ion.