Dual-potential ratiometric electrochemiluminescence sensor based on ZnO@g-C₃N₄ and GO@luminol for metronidazole...

A dual-potential ratiometric electrochemiluminescence (RECL) sensor for metronidazole (MNZ) detection has been developed. The sensor was constructed by sequentially depositing a ZnO@g-C₃N₄ cathodic layer serving as the response signal and a graphene oxide(GO)@luminol anodic layer serving as the reference signal. In the persulfate system, the maximum initial cathodic signal was obtained from ZnO@g-C₃N₄, with the addition of MNZ, the cathodic signal was selectively quenched whereas the anodic signal remained unchanged. The mechanism was verified by radical-scavenging experiments. Under optimal conditions, the ratiometric signal (I_a/I_c) exhibited a linear relationship with the logarithm of MNZ concentration (lgC_MNZ) over 1.0 × 10^- 10 to 1.0 × 10^- 6 mol L^- 1. The limit of detection was 3.3 × 10^- 11 mol L^- 1 (S/N = 3). The proposed RECL sensor was further applied to real samples, demonstrating its feasibility and potential for MNZ determination in complex matrices.