Abstract: A highly sensitive electrochemical sensor for the detection of norfloxacin (NFX) was constructed using CMC@Cu/CB composites, which were prepared from carboxymethyl cellulose (CMC)-coated copper nanoparticles (Cu NPs) and carbon black (CB). The structure and morphology of CMC@Cu/CB were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (SPS), and X-ray diffraction (XRD). The CMC@Cu/CB/GCE sensor was prepared by drop-casting the composite suspension on the glassy carbon electrode (GCE) surface. The results showed that the CMC@Cu/CB/GCE sensor, which was in the form of uniformly dispersed spheres, had a good current response to NFX, with a linear range of 0.4–100.0 μmol/L and a limit of detection (LOD) of 0.24 μmol/L (RSN = 3). In addition, the modified electrode had good sensitivity and stability for the detection of NFX in real samples, and the spiked recoveries of NFX in milk extracts ranged from 98.8%–112.5%. Furthermore, thanks to the low price of raw materials used in the experimental process and the preparation extremely of low cost of the sensor, it is promising for actual applications.

Key words: electrochemical sensor; norfloxacin; copper nanoparticles; carboxymethyl cellulose