Simultaneous determination of lead and cadmium in urine by a glassy carbon electrode modified with Sb/CMWCNTs@Nafion

The accumulation of lead (Pb 2+ ) and cadmium (Cd 2+ ) in the human body can lead to significant long-term health risks. Urine is an essential biological sample that reflects the accumulation of metals in the body, and an invaluable source of monitoring information. Consequently, it is crucial to develop methods that enable the highly sensitive and selective detection of Pb 2+ and Cd 2+ concentrations in urine. In this study, a composite material of carboxylated multi-walled carbon nanotubes (CMWCNTs) and Nafion was synthesised and used to fabricate a modified glassy carbon electrode (GCE) via drop-casting, followed by the potentiostatic deposition of an antimony (Sb) film. Differential pulse stripping voltammetry (DPSV) was used for the quantitative analysis of Pb 2+ and Cd 2+ in urine, with experimental conditions carefully optimised. The results showed a strong linear relationship between the peak current and the concentration of Pb 2+ /Cd 2+ within a 2–100 μg·L −1 range. The detection limits for Pb 2+ and Cd 2+ were 0.46 and 0.38 μg·L −1 , respectively. When applied to actual urine samples, the modified electrode demonstrated excellent performance, achieving spiked recovery rates of 96.53–103.35 % for Pb 2+ and 93.87–96.59 % for Cd 2+ . These findings indicated that the proposed method effectively detected trace amounts of Pb 2+ and Cd 2+ in urine, offering a promising tool to monitor Pb 2+ and Cd 2+ in biological specimens.