A simple and easy method was implemented for the contemporary detection of cadmium (Cd²⁺) and lead (Pb²⁺) ions using 1,3,6,8-pyrenetetrasulfonic acid sodium salt-functionalized carbon nanotubes nanocomposites (PyTS–CNTs). The morphology and composition of the obtained PyTS–CNTs were characterized using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results confirmed that the fabricated PyTS–CNTs exhibited good selectivity and sensitivity for metal ion-sensing owing to the insertion of sulfonic acid groups. For Cd²⁺ and Pb²⁺, some of the electrochemical sensing parameters were evaluated by varying data such as the PyTS–CNT quantity loaded on the pyrolytic graphite electrode (PGE), pH of the acetate buffer, deposition time, and deposition potential. These parameters were optimized with differential pulse anodic sweeping voltammetry (DPASV). Under the optimal condition, the stripping peak current of the PyTS–CNTs/Nafion/PGE varies linearly with the heavy metal ion concentration, ranging from 1.0 μg L⁻¹ to 90 μg L⁻¹ for Cd²⁺ and from 1.0 μg L⁻¹ to 110 μg L⁻¹ for Pb²⁺. The limits of detection were estimated to be approximately 0.8 μg L⁻¹ for Cd²⁺ and 0.02 μg L⁻¹ for Pb²⁺. The proposed PyTS–CNTs/Nafion/PGE can be used as a rapid, simple, and controllable electrochemical sensor for the determination of toxic Cd²⁺ and Pb²⁺.

Almond shell-based charcoal was prepared by carbonizing almond shells in a nitrogen atmosphere. Nanoporous carbon (NPC) was formed via activating the obtained charcoal using potassium hydroxide as an activating agent, followed by the synthesis of nitrogen-doped nanoporous carbon (N-NPC) via a hydrothermal reaction using urea as the nitrogen source. The obtained N-NPC possessed a large surface area (1075 m² g⁻¹), narrow pore-size distribution (1–2 nm) and nitrogen content reaching 2.23 wt%. Using N-NPC with Nafion to modify a glassy carbon electrode, a highly sensitive electrochemical sensor was fabricated for the determination of Pb(II) in aqueous solutions with differential pulse anodic stripping voltammetry (DPASV). The peak current of Pb(II) showed linearity over concentrations from 2.0 to 120 μg L⁻¹ and the detection limit (S/N = 3) was estimated to be 0.7 μg L⁻¹ for Pb(II), which was 15-fold lower than the guideline value of drinking water given by the World Health Organization (WHO). The experimental data indicated that this easy and low-cost method is an accurate and fast method for the detection of trace Pb(II).

Acetaminophen (N-acetyl-p-aminophenol, APAP) is regularly used for antipyretic and analgesic purposes. Overdose or long-term exposure to APAP could lead to liver damage and hepatotoxicity. In this study, the approach of enhanced electrochemical detection of APAP by nanostructured biomass carbon/silver was developed. Porous biomass carbon derived from Elaeagnus Angustifolia gum was prepared by pyrolysis with co-doping of electron-rich elements of nitrogen, sulfur, and phosphorus. The electrodeposition of silver onto a glassy carbon electrode modified with porous carbon could enhance the sensing signal towards APAP. Two linear ranges from 61 nM to 500 μM were achieved with a limit of detection of 33 nM. The developed GCE sensor has good anti-interference, stability, reproducibility, and human urine sample analysis performance. The silver-enhanced biomass carbon GCE sensor extends the application of biomass carbon, and its facile preparation approach could be used in constructing disposable sensing chips in the future.