Stripping analysis of Pb2+ and Hg2+ in deveined shrimp and eggshells using a H2bpabza/MWCNT–modified graphite electrode

A novel synthesis was performed of asymmetrical carboxamide ligand N,N′-bis(2-pyridinecarboxamide)-2-aminobenzylamine (H₂bpabza) derived from 2-pyridinecarboxylic acid and 2-aminobenzylamine. The N,N′-bis(2-pyridinecarboxamide)-2-aminobenzylamine (H₂bpabza) ligand was confirmed by ultraviolet-Visible (UV-Vis), Fourier transform infrared (FT-IR), and Raman spectroscopy. The fabrication of N,N′-bis(2-pyridinecarboxamide)-2-aminobenzylamine (H₂bpabza) embedded in a multi-walled carbon nanotube (MWCNT)-modified graphite electrode (GE) for use as an electrochemical sensor of Pb²⁺ and Hg²⁺ was demonstrated. The performance of the H₂bpabza/MWCNT electrode and (Pb²⁺ and Hg²⁺–H₂bpabza)/MWCNT was investigated by scanning electron microscopy (SEM) and square wave anodic stripping voltammetry (SWASV). In comparison to the MWCNT electrode, the H₂bpabza/MWCNT electrode exhibited higher sensitivity and conductivity, as determined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Stripping analysis and detailed experiments were conducted to establish the optimal parameters for deposition and stripping of metal ions, such as supporting electrolytes, pH, and accumulation time. The linear range was 2 to 140 μg L⁻¹, with a detection limit of 0.1 μg L⁻¹ for Pb²⁺ and 0.3 μg L⁻¹ for Hg²⁺ (S/N = 3). The H₂bpabza/MWCNT-modified GE showed excellent sensitivity, selectivity, stability, and reproducibility for the determination of Pb²⁺ and Hg²⁺. Ultimately, the H₂bpabza/MWCNT-modified GE was used to demonstrate the electrochemical sensing of Pb²⁺ and Hg²⁺ in deveined shrimp and eggshells.