Sub-picomole detection of norfloxacin using a molecularly imprinted electrochemical sensor

Norfloxacin (NOR) is a fluoroquinolone antibiotic, and its long-term intake poses serious threats to human health. Therefore, sensitive determination of NOR is of great significance. This work develops a molecularly imprinted electrochemical sensor (MIES) for detecting NOR based on molecularly imprinted polypyrrole/carboxylated multi-walled carbon nanotubes-chitosan/glassy carbon electrode (MIP/cMWCNT-CS/GCE). The cMWCNT-CS serves as a conductive layer for signal amplification, while MIP acts as the recognition element for specific identification of NOR. NOR is indirectly detected by the reduction peak current of potassium ferricyanide probe_. This MIES exhibits an ultra-wide linear range (1.00 × 10^-13-1.00 × 10^-5 M) and an ultra-low detection limit (1.78 × 10^-14 M) with rapid response (adsorption time 4 min), high selectivity, and excellent reproducibility. Furthermore, the MIES is successfully applied to determine NOR in honey, milk, and tap water samples with satisfactory recoveries (87.30% ∼ 121.00%). This work provides a promising analytical avenue for rapid and ultrasensitive monitoring of NOR in food and environmental samples.