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.