Coordination matrix/signal amplifier strategy for simultaneous electrochemical determination of cadmium(ii), lead(ii), copper(ii), and mercury(ii) ions based on polyfurfural film/multi-walled carbon nanotube modified electrode

Abstract

In this work, we firstly propose and confirm a novel coordination matrix/signal amplifier strategy to construct a highly sensitive lead(II) electrochemical sensor. Lead(II) ions can be efficiently accumulated and deposited on the electrode surface by strong coordination bonds between the unoccupied d-orbital of lead(II) ions and conjugated π-electron backbones of polyfurfural film (coordination matrix), and then the anodic stripping current can be significantly enhanced by multi-walled carbon nanotubes (MWCNTs, signal amplifier), finally realizing the highly sensitive determination of lead(II). The polyfurfural film/MWCNT modified glassy carbon electrode (GCE) sensor provided a wide linear detection range from 0.05 to 10 μg L⁻¹ and a low detection limit of 0.01 μg L⁻¹ (S/N = 3) for lead(II). Compared with a classical mercury film sensor (a classical and effective method for determining heavy metal ions), our proposed sensor was more sensitive and achieved better results. Moreover, based on the coordination matrix/signal amplifier strategy, the polyfurfural film/MWCNTs/GCE sensor was further successfully utilized for the simultaneous determination of Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺, demonstrating a wide linear detection range for Cd²⁺ (0.5–15 μg L⁻¹), Pb²⁺ (0.1–15 μg L⁻¹), Cu²⁺ (0.1–12 μg L⁻¹), and Hg²⁺ (1.5–12 μg L⁻¹) and a low detection limit for Cd²⁺ (0.03 μg L⁻¹, S/N = 3), Pb²⁺ (0.01 μg L⁻¹, S/N = 3), Cu²⁺ (0.06 μg L⁻¹, S/N = 3), and Hg²⁺ (0.1 μg L⁻¹, S/N = 3). Finally, the proposed sensor was successfully applied to simultaneously determine Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ in real tap water samples. This work provides a novel and effective analytical strategy for constructing novel electrochemical sensors and shows broad application prospects in heavy metal ion determination for the future.