Electrochemical sensing of Pb2+, Cu2+, and Hg2+ by an aminoclay-based porous covalent organic polymer/ multi-walled carbon nanotubes modified glassy carbon electrode

Abstract

We present a novel electrochemical sensor for the simultaneous detection of Lead (Pb2+), Copper (Cu2+), and Mercury (Hg2+) ions in seafood samples using differential pulse anodic stripping voltammetry (DPASV) technique. The sensor incorporates an aminoclay-based porous covalent organic polymer (AC-PCOP) derived from the polymerization of aminoclay and 1,3,5-benzenetricarboxylic acid (trimesic acid). To enhance conductivity, the AC-PCOP is combined with multi-walled carbon nanotubes (MWCNTs) and utilized for modifying the surface of the glassy carbon electrode (GCE). The AC-PCOP was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and infrared spectroscopy (IR). These analyses confirmed the presence of a hierarchical architecture in the AC-PCOP, which exhibited a spherical shape. The proposed modifier facilitates the deposition-stripping process and electron diffusion between electrolyte and heavy metal ions. Optimized conditions yielded limit of detections (LODs) of 0.0006, 0.0016, and 0.0003 nM, with linear ranges from 0.002 to 1000 nM, 0.005 to 1000 nM, and 0.001 to 1000 nM for Pb2+, Cu2+, and Hg2+, respectively. The sensor successfully measured these ions in seafood samples. Control experiments and validation were performed using cold vapor atomic absorption spectrometry (CVAAS) to determine the ions in the chosen food samples.