Lead (Pb II) and cadmium (Cd II) pose significant threats to human health and the environment, as both cations can enter the food chain through soil and water contamination resulting from industrial activities [1]. Once introduced into the food chain, these substances can accumulate and lead to detrimental effects in humans, including neurological and developmental problems associated with Pb (II), as well as kidney damage, bone disorders, and an elevated risk of cancer linked to Cd (II) [2]. This study focuses on the characterization and synthesis of the MWCNs Poly(2-aminothiophenol) @AgNPs nanocomposite using various analytical techniques, including scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The synthesized MWCNs-Poly(2-aminothiophenol) @AgNPs nanocomposite was utilized as an electrocatalytic modifier for the highly selective and sensitive detection of Pb²⁺ and Cd²⁺ ions at nanomolar concentrations via square wave anodic stripping voltammetry. Operational parameters, such as the concentration of MWCNs-Poly(2-aminothiophenol) @AgNPs, the type and concentration of the electrolyte, the pH of the solution, and the conditions for preconcentration, were systematically optimized. A linear response was observed for Pb²⁺ and Cd²⁺ within the ranges of 0.5–60.0 nmol L⁻¹ and 4.0–50.0 nmol L⁻¹, respectively, with detection limits of 0.13 nmol L⁻¹ for Pb²⁺ and 1.5 nmol L⁻¹ for Cd²⁺. Furthermore, the MWCNs-Poly(2-aminothiophenol) @AgNPs nanocomposite sensor demonstrated the capability to selectively detect these target metals in the presence of various common cationic and anionic interfering species. The sensor was successfully employed for the determination of Pb²⁺ and Cd²⁺ ions in a range of samples, including turmeric, drinking water, salt, ginger, garlic, lemon, red pepper, black pepper, black tea, and dried powdered spices.
