Synthesis, characterization, and application of poly [Cu(Chr)2Cl]Cl/PGE based electrochemical sensor for the determination of Norfloxacin in pharmaceuticals and Milk samples

Norfloxacin (Nor) is a drug belonging to the fluoroquinolones class, commonly used to treat bacterial infections of humans and animals. However, improper use, unmetabolized excretion, and overuse of Nor can lead to bacterial resistance. To mitigate this risk, sensitive, selective, and alternative analytical techniques are required. In this work, a Cu(II)-chrysine complex was synthesized, characterized and applied to modify pencil graphite electrode for electrochemical determination of Nor in pharmaceuticals and milk samples. The tip of the PGE electrode has been modified using the potentiodynamic electropolymerization method and a monomer modifier of [Cu(Chr) 2 Cl]Cl using the optimized potential window and film thickness. The modified electrode was characterized using EIS, UV–Vis, CV, digital optical microscopy, and contact angle. Both the developed electrochemical method and UV–Vis spectroscopic method were calibrated and used for the determination of concentration of Nor in two brands of pharmaceuticals, in milk samples, and in the presence of different potential interferences. The percent recoveries of Nor in Nofxin and Gyrablock were in the range of 93.7–99.3 % and 96.6–109.9 %, respectively, and in milk samples, recoveries ranged from 81.80 % to 91.13 %. The developed method exhibited a slope of −0.511 μA/μM, a detection limit (LoD) of 0.096 μM, and a linear dynamic range of 1–100 μM. The developed method was selective towards Nor in the presence of caffeine and paracetamol, making it a promising alternative for the determination of Nor in different matrices. • Synthesis and characterization of a Cu(II)-chrysine complex and applied as a modifier • Development of a sensitive and selective electrochemical sensor for Norfloxacin detection • Electrode modification via potentiodynamic electropolymerization • Analytical validation using both electrochemical and UV–Vis spectroscopy methods • Demonstrated selectivity in the presence of common interferences (caffeine and paracetamol)