Development of Iron (III) Selective Coated Graphite Electrode Based on Schiff Base N, N'-BIS (2,4-Dimethoxybenzilidene) Ethylenediamine

A graphite electrode coated with a PVC-based membrane was developed for the potentiometric detection of Fe³⁺ ions, incorporating the Schiff base ligand N, N'-bis(2,4-dimethoxybenzilidene) ethylenediamine (L). The optimized membrane composition included 4% L, 2.5% NaTPB, 51% NPOE, and 42.5% PVC. This sensor effectively detected Fe³⁺ ions across a concentration range of 2.5 × 10⁻⁷ to 1.0 × 10⁻¹ M, with a detection limit as low as 7.8 × 10⁻⁸ mol L⁻¹ and a response time of just 12 seconds. Stability tests revealed that the electrode maintained consistent performance for over 90 days, without significant degradation. The sensor also showed high selectivity towards Fe³⁺ ions, remaining effective in the presence of potential interfering species. Additionally, it functioned reliably within a pH range of 3.0 to 7.0 and was compatible with non-aqueous solvents (up to 20% v/v). The electrode was effectively utilized as an indicator for potentiometric titration of Fe³⁺ with EDTA and for accurate determination of Fe³⁺ ions in various sample matrices.