Ultrasensitive electrochemical detection of metronidazole using binder-free zinc-4,4’-oxybis(benzoic acid) MOF/GCE in real samples

A novel electrochemical sensor is constructed by modifying the glassy carbon electrode (GCE) using a binder-free metal–organic framework of V-shaped linker 4,4’oxybis(benzoic acid) (OBA) and various transition metals (M—Zn, Mn, or Ni). The hydrothermally synthesized M-OBA MOFs demonstrated superior electron transfer ability and enhanced electro-reduction behaviour, making it highly effective for metronidazole (MTZ) detection. The optimized sensor demonstrated a linear response from 0.04 to 122.18 µM, a low detection limit (LOD) of 0.009 µM, and high sensitivity (0.48 µA µM −1 cm −2 ) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The sensor also exhibited excellent selectivity in the presence of various ions, organic compounds, and other antibiotics. The Zn-OBA MOF sensor proves practical applicability for detecting MTZ in milk, honey, tap water, and MTZ tablets. Graphical Abstract