IRON(III)-SELECTIVE MEMBRANE POTENTIOMETRIC SENSOR BASED ON 5,10,15,20-TETRAKIS-(PENTAFLUOROPHENYL)-21H,23H-PORPHYRIN

Abstract

A new PVC membrane electrode for Fe³⁺ ions based on 5,10,15,20-tetrakis (pentaflurophenyl)-21H,23H-porphyrin as membrane carrier was prepared. The sensor exhibits a super-Nernstian slope of 25.0 ± 0.5 mV per decade over a 1.0 × 10⁻⁴–1.0 × 10⁻⁶ M concentration range. It has a response time of about 10 s and can be used for at least 8 weeks without any divergence in potentials. The proposed sensor revealed very good selectivities for Fe³⁺ over a wide variety of other cations over a pH range 3–4. It was applied to the direct determination of iron in tap water samples and, as an indicator electrode, in potentiometric titrations of Fe³⁺ ion. The electrode was also successfully applied to the speciation of iron in aqueous solutions.

Keywords:

• Fe(III) ion-selective electrode
• PVC membrane
• Potentiometry
• 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphyrin

Acknowledgments