A New Fe (III)-Selective Membrane Electrode Based on Fe (II) Phthalocyanine

Abstract

A new miniaturized all solid-state contact Fe (III)-selective PVC membrane electrode based on Fe (II) phthalocyanine as a neutral carrier was described. The effects of the membrane composition and foreign ions on the electrode performance was investigated. The best performance was obtained with a membrane containing 32% poly (vinyl chloride), 64% dioctylsebacate, 3% Fe (II) phthalocyanine, and 1% potassium tetrakis (p-chlorophenyl) borate. The electrode showed near Nernstian response of 26.04 ± 0.95 mV/decade over the wide linear concentration range 1.0 × 10−6 to 1.0 × 10−1 M, and a very low limit of detection 1.8±0.5 × 10−7 M. The potentiometric response of the developed electrode was independent at pH 3.5–5.7. The lifetime of the electrode was approximately 3 months and the response time was very short (< 7 s). It exhibited excellent selectivity towards Fe (III) over various cations. The miniaturized all solid-state contact Fe (III)-selective membrane electrode was successfully applied as an indicator electrode for the potentiometric titration of 1.0 × 10−3 M Fe (III) ions with a 1.0 × 10−2 M EDTA and the direct determination of Fe (III) ions in real water samples.