Electrochemical sensing of Hg(ii) in chicken liver and snail shell extract samples using novel modified SDA/MWCNT electrodes

Abstract

Heavy metal ions (Hg(II)) were detected in fresh chicken liver and snail shell extract samples using novel synthesised SDA/MWCNT-modified electrodes. The synthesized N,N′-bis(salicylaldehyde)-1,2-diaminobenzene (SDA) ligand was characterized via FT-IR, ¹H-NMR, and ¹³C-NMR spectroscopy. The hydroxyl and imine functional groups present in SDA act as active sites and bind to the MWCNT surface. The surface morphology of the modified SDA/MWCNT electrode exhibited a star-like crystal structure and the preconcentration of Hg(II)-SDA/MWCNTs lead to a crystal cloud structure, as characterized by SEM with EDX. The enhancement of current and conductance of the SDA/MWCNT- and MWCNT-modified electrode was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The conductance (σ) values for the MWCNT- and SDA/MWCNT-modified electrodes are 234.1 × 10⁻⁵ S cm⁻¹ and 358.4 × 10⁻⁵ S cm⁻¹, respectively, as determined by electrochemical impedance spectroscopy. Consequently, an electrochemical sensor with outstanding performance in terms of reproducibility, stability and anti-interference ability was fabricated. The stripping analysis of Hg(II) was performed using square wave anodic stripping voltammetry (SWASV) and cyclic voltammetry (CV). Using SWASV, a linear range of Hg(II) response was found to be 1.3 to 158 μg L⁻¹, and the limit of detection (LOD) was 0.24 μg L⁻¹. Finally, the results of the recovered value of Hg(II) in freshly prepared chicken liver and snail shell extract samples by SWASV were compared with the atomic absorption spectroscopy (AAS) results.