Detection of Cd²⁺ and Pb²⁺ in egg yolk and maize samples by a novel SDA/MWCNTs-based electrochemical sensor

A novel Schiff base-functionalized, multiwalled carbon nanotube-modified, paraffin-impregnated graphite electrode (SDA/MWCNTs/PGE) was developed for simultaneous electrochemical detection of Cd²⁺ and Pb²⁺ in food analyses. MWCNTs improved the electroactive surface area and electron-transfer kinetics. Hydroxyl and azomethine donor groups in the SDA ligand provided efficient coordination sites for metal-ion binding. FT-IR, H¹ NMR, and FESEM techniques were used to characterise the fabricated sensor, indicating successful synthesis and surface modification. With a limit of detection of 0.33 ppb for Cd²⁺ and 0.07 ppb for Pb²⁺, the sensor exhibited a linear range of 1.3-101 ppb under optimised square-wave anodic stripping voltammetry (SWASV) conditions. With relative standard deviation values <3%, the sensor exhibited good repeatability, stability, and excellent selectivity for common interfering metal ions. By analysing egg yolk and maize samples, the practical application of the suggested sensor was confirmed. Results showed good agreement with data from atomic absorption spectroscopy and satisfactory recoveries. The developed SDA/MWCNTs/PGE sensor offers a straightforward, affordable, and dependable platform for monitoring traces of heavy metals in food matrices.