Ratio Electrochemical Detection of Nitrofurazone Based on Carbon Nanotubes/Electroactive Schiff Base Polymer

Nitrofurazone (NFZ), as an antibiotic, is carcinogenic upon prolonged exposure. Thus, detecting NFZ and its metabolites is essential for ensuring food safety and preventing potential health risks to humans. A dual‐signal electrochemical sensor consisting of a composite of carbon nanotubes and an electroactive Schiff base polymer (SBP Thi‐DHA , synthesized from thionine and 2,5‐dihydroxyterephthalaldehyde)/carbon nanotubes) enabled highly sensitive detection of nitrofurazolidone (NFZ). The sensor was fabricated using 2,5‐dihydroxyterephthalaldehyde (DHA) and electroactive thionine (Thi) monomer as precursors to prepare spherical SBP Thi‐DHA nanomaterials with an average diameter of approximately 2 μm through a Schiff base reaction. The resulting material possessed high surface area, superior electron transport capability, and abundant surface functional groups, which enabled uniform loading of amino‐functionalized carbon nanotubes (NH 2 ‐CNT) and significantly enhanced the catalytic performance and detection sensitivity of the sensor. Empirical evidence demonstrated that the ratiometric electrochemical sensor achieved a remarkably low detection of 4.3 nM for NFZ at a reference signal of −0.6 V, with wide linear ranges of 13.1 nM‐80 and 80–400 μM. The introduction of ratiometric signals effectively minimized interference caused by electrode surface state variations, electrolyte concentration fluctuations, and temperature changes during detection, significantly improving measurement accuracy and reproducibility. Furthermore, the excellent stability of SBP Thi‐DHA /CNT on the electrode surface endowed the sensor with outstanding reusability.