In this study, blue octahedral crystal of Cu-based metal-organic framework (Cu-MOF) was synthesized through a simple solvothermal method. The Cu-MOF was used as a modifier on GCE for the simultaneous determination of Tl (I) and Hg (II) at the trace level by square wave anodic stripping voltammetry (SWASV). The synthesized Cu-MOF was characterized by scanning electron microscope (SEM), transition electron microscope (TEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). The parameters affecting the electrochemical process, such as the kind of electrolyte solution, KCl concentration, the potential, and the time for accumulation were investigated in detail. Under the optimal conditions, the present sensor showed excellent electrochemical performance for Tl (I) and Hg (II) in the leaner ranges from 0.5–700 ppb and 1–400 ppb, respectively. Low detection limits of 0.11 ppb for Tl (I) and 0.17 ppb for Hg (II) were achieved. The method is successfully applied to the determination of Tl (I) and Hg (II) in real samples and good recoveries are obtained from different spiked samples.

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