Electrochemical sensor using graphene/Fe3O4 nanosheets functionalized with garlic extract for the detection of lead ion

Based on the modulated electronic properties of Fe3O4-graphene (Fe3O4/GN composite) as well as the outstanding complexation between Pb2+ and natural substances garlic extract (GE), a novel electrochemical sensor for the determination of Pb2+ in wastewater was prepared by immobilization of Fe3O4/GN composite integrated with GE onto the surface of glassy carbon electrode (GCE). Fe3O4/GN composite was employed as an electrochemical active probe for enhancing electrical response by facilitating charge transfer while GE was used to improve the selectivity and sensitivity of the proposed sensor to Pb2+ assay. The electrochemical sensing performance toward Pb2+ was appraised by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). Under the optimized condition, the sensor exhibited two dynamic linear ranges (LDR) including 0.001 to 0.5nM and 0.5 to 1000nM with excellent low detection limit (LOD) of 0.0123pM (S/N=3) and quantification limit (LOQ) of 0.41pM (S/N=10). Meanwhile, it displayed remarkable stability, reproducibility (RSD of 3.61%, n=3), and selectivity toward the assay for the 100-fold higher concentration of other heavy metal ions. Furthermore, the novel sensor has been successfully employed to detect Pb2+ from real water samples with satisfactory results.