Liquid membrane potentiometric sensor for determination of Fe3+ ion

Solution studies showed a selective interaction between the new synthesized ionophore, 2-(thiophen-2-yl)methyleneamino]isoindoline-1,3-dione (TMID) and Fe(III) ion. Therefore, TMID was used as an iron selective ion-carrier in a plasticized liquid membrane sensor. The linear response range of the proposed electrode was 1.0 × 10^?6–1.0 × 10^?2 M. The Nernstian slope of 20.1 ± 0.3 mV/decade, and a detection limit of 5 × 10^?7 M was obtained. The sensor could be used in the pH range of 2.3–4.8, and the response time was about 10 s. The lifetime of the electrode was at least 7 weeks. The sensor accuracy was investigated in two ways: (i) with the potentiometric titration of a Fe³⁺ solution with EDTA and (ii) with Fe(III) monitoring in some cationic mixtures. Finally, the newly fabricated electrode was effectively applied as an indicator electrode for the direct Fe³⁺ determination in real samples.