▎ 摘　　要

We demonstrate a mediator-free electrochemical sensitive sensing for detection of metronidazole (MNZ) and chloramphenicol (CAP) in real samples. A few-layered defect-free graphene nanoflakes (GNFs) were synthesized by surfactant-assisted exfoliation method, which was characterized by several methods like XRD, Raman spectroscopy, FE-SEM and TEM images. Cyclic voltammetry and electrochemical impedance spectroscopy were studied to understand the electron transfer behavior of GNFs modified glassy carbon electrode (GCE). Electrochemical behavior of MNZ and CAP was investigated at GNFs/GCE in PBS and observed peak potentials at - 0.32 V and - 0.51 V vs. Ag/AgCl. A wider reduction potential window of MNZ and CAP were observed by differential pulse voltammetry which was found to be 280 mV at GNFs/GCE. Amperometry method was employed for detection of the unknown concentration of analytes under hydrodynamic condition. A linear calibration plot was obtained by plotting the concentrations of MNZ and CAP in ranging from 0.5 to 5.5 nM with R-2 of 0.9983 and 0.9980, respectively. The detection limit of MNZ and CAP were found to be 0.15 nM and 0.38 nM, this system have shown good stability, excellent reproducibility and free interference from GNFs/GCE. The present method was successfully applied for the determination of MNZ and CAP in drugs and urine samples.