Modified electrochemical sensor with polydopamine-multiwalled carbon nanotubes for simultaneous determination of Cd (Ⅱ) and Pb (Ⅱ) in herbal medicines

The detection of toxic heavy metal ions, such as cadmium (Cd 2 + ) and lead (Pb 2+ ), is crucially important due to their environmental persistence and severe health risks. While multi-walled carbon nanotubes (MWCNTs) hold potential for electrochemical sensing, their practical application is hindered by aggregation tendencies and limited analyte affinity. To address these limitations, a composite utilizing polydopamine-functionalized MWCNTs (PDA@MWCNTs) was developed. This material synergistically enhances dispersion stability and improves metal ion capture capabilities. Based on this composite, an electrochemical sensor was fabricated for simultaneous detection of Cd 2+ and Pb 2+ . Sensor characterization using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) demonstrated good performance, achieving high sensitivity and selectivity. Low detection limits of 0.21 nM for Cd 2+ and 0.13 nM for Pb 2+ were attained, enabling reliable simultaneous quantification. The electrochemical sensor’s practical utility was validated through accurate measurements in lake water sample and complex herbal medicine matrices, highlighting its applicability for environmental monitoring and food safety. This platform offers distinct advantages including simple fabrication, cost-effectiveness, and sub-nanomolar sensitivity necessary for regulatory compliance.