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

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