Document Type : Research Paper
Fe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrix
membrane containing neutral carrier tetra phenyl porphyrin (TPP) ionophore. The addition of
sodium tetraphenylborate (NaTPB) and the plasticizer DBP has been found to substantially
improve the performance of the sensor. The best performance was obtained with the sensor having
a membrane of composition of TPP: NaTPB: DBP: PVC in the ratio 6:3:61:30 respectively. The
sensor shows a linear response over a wide concentration range of 1.0 x 10-6 to 1.0 x 10-2 M with
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
response time of <12 s and can be used for more than seven weeks without any measurable
divergences 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) indicate
excellent selectivity for Fe2+ ion.