A rapid, simple and sensitive electrochemical sensor based on glassy carbon electrode modified with tin oxide nanoparticles @ multiwalled carbon nanotubes have been used for determination of trace Hg(II) and Tl(I) using the square wave anodic stripping voltammetric (SWASV) technique. Under optimized condition, the limit of detection and quantification ranged from 0.9−1.2 ng L −1 and 3.3-4.0 ng L −1 , respectively. The inter-day (n=10) and intra-day (n=7) precisions expressed in relative standard deviations at 50 μg L −1 of Hg(II) and Tl(I) ranged from 2.1-3.5 and 3.0-4.3%, respectively. The GCE/SnO 2 @MWCNTs was applied for the determination of the target trace elements in thirteen surface water samples. The accuracy of analytical results obtained using the developed electrochemical sensor was comparable to those obtained by the ICP-MS.

The rapid detection of trace metals is one of the most important aspect in achieving environmental monitoring and protection. Electrochemical sensors remain a key solution for rapid detection of heavy metals in environmental water matrices. This paper reports the fabrication of an electrochemical sensor obtained by the simultaneous electrodeposition of MnO2 nanoparticles and RGO nanosheets on the surface of a glassy carbon electrode. The successful electrodeposition was confirmed by the enhanced current response on the cyclic voltammograms. The XRD, HR-SEM/EDX, TEM, FTIR, and BET characterization confirmed the successful synthesis of MnO2 nanoparticles, RGO nanosheets, and MnO2@RGO nanocomposite. The electrochemical studies results revealed that MnO2@RGO@GCE nanocomposite considerably improved the current response on the detection of Zn(II), Cd(II) and Cu(II) ions in surface water. These remarkable improvements were due to the interaction between MnO2 nanomaterials and RGO nanosheets. Moreover, the modified sensor electrode portrayed high sensitivity, reproducibility, and stability on the simultaneous determination of Zn(II), Cd(II), and Cu(II) ions. The detection limits of (S/N = 3) ranged from 0.002–0.015 μg L−1 for the simultaneous detection of Zn(II), Cd(II), and Cu(II) ions. The results show that MnO2@RGO nanocomposite can be successfully used for the early detection of heavy metals with higher sensitivity in water sample analysis.