Highly Selective Solid Contact Sensor for Low Level Concentration Measurements of Iron(III) in Pharmaceutical and Biological Media

A symmetrical tetradentate Schiff base ligand was derived by the condensation of the corresponding o-vanillin with urea. The synthesized Schiff base ligand was studied to characterize its ability as a cation carrier in poly(vinylchloride) membrane solid contact sensor. The constructed sensor showed excellent response characteristics to iron(III) ion. The electrode exhibited Nernstian slope of 19.5 mV/decade over a wide concentration range of iron(III) from 3.0 x 10(-6) to 1.3 x 10(-2) M with a detection limit of 1.2 x 10(-6) M. The sensor has fast response time, good reproducibility and excellent selectivity toward iron(III) ion with respect to many alkali, alkaline earth, transition and heavy metal ions. The potentiometric response of the sensor is independent of pH of the test solution in the range of 2.5-4.5. The applicability of the sensor was investigated by the determination of iron(III) concentration in pharmaceutical, biological and water samples.