A novel iron (III)-PVC membrane potentiomeric sensor based on N-(2-hydroxyethyl)ethylenediamine-N,N′,N"-triacetic acid

This work introduces a unique ionophore for the selective determination of Fe(III) ions. This ionophore was N-(2-hydroxyethyl)ethylenediamine-N,N ',N ''-triacetic acid (NTA), presenting a high affinity towards the trivalent iron cations. The designed sensor exhibited a wide linear response with a slope of 19.5 +/- 0.4 mV per decade over the concentration range of 1.0 x 10(-9)-1.0x10(-2) mol L-1, while the illustrated detection limit was 3.0 x 10(-10) mol L-1 of the Fe(III) ions concentration. It was concluded that the sensor response was pH independent in the range of 1.8-4.5. The sensor possessed the advantages of short conditioning time, fast response time (10 s) and, especially, good selectivity towards the transition and heavy metal ions as well as some mono, di and trivalent cations. Concerning the electrode lifetime, no considerable potential divergence was noticed for at least 10 weeks. The sensor accuracy was investigated in the potentiometric titration of a Fe(III) solution with EDTA. (C) 2008 Elsevier B.V. All rights reserved.