▎ 摘　　要

In the present study, a highly efficient electrochemical sensor for methadone measurement through the use of a glassy carbon electrode modified with two layers of graphene/Ag nanoparticles ((Gr/AgNPs)(2)/GCE) nanocomposite is introduced. The morphological, elemental and electrochemical properties of the as-prepared nanocomposite were evaluated by scanning electron microscopy, energy dispersive spectroscopy. The influence of different experimental parameters such as pH and scan rate on the voltammetric response of methadone was also addressed. Exhibiting a peak potential at + 0.79 V (vs. Ag/AgCl), the as-prepared electrode manifested an improvement in its catalytic activity toward methadone oxidation. Under optimal conditions, the developed sensor exhibited an excellent response toward methadone in the concentration range of 1.0-200.0 mu M with a detection limit of 0.12 mu M. Moreover, the proposed electrode offered superior selectivity for methadone reflecting its efficiency for the real samples such as human blood serum.