Development of a Pb²⁺-selective potentiometric sensor for environmental monitoring of lead in water samples

A Pb²⁺-selective potentiometric sensor based on a PVC membrane incorporating 5,8-dibromo-2-((furan-2-ylmethyl)amino)naphthalene-1,4-dione as a neutral ionophore was successfully fabricated and characterized. The membrane electrode exhibited excellent selectivity toward Pb²⁺ in the presence of various potentially interfering metal ions and displayed favorable electroanalytical performance. A Nernstian slope of 28.8 ± 1.09 mV/decade was obtained over the concentration range of 1.0 × 10⁻⁶-1.0 × 10⁻¹ M, with a detection limit of 5.73 × 10⁻⁷ M. In addition, the sensor reached a stable potential within 6 s and operated reliably over the pH range of 4.0-9.0, while maintaining good repeatability throughout the measurements. SEM-EDX analysis and elemental mapping further provided evidence for the presence and distribution of Pb on the membrane surface after Pb²⁺ exposure, supporting the interaction of the ionophore-containing membrane with Pb²⁺. Its analytical applicability was verified by the determination of Pb²⁺ in environmental water samples, yielding satisfactory results. These findings demonstrate that the fabricated membrane sensor provides a simple, sensitive, selective, and cost-effective approach for the potentiometric determination of Pb²⁺ in environmental water samples.