Square-wave adsorptive anodic stripping voltammetric determination of norfloxacin using a glassy carbon electrode modified with carbon black and CdTe quantum dots in a chitosan film

A glassy carbon electrode was modified with carbon black and CdTe quantum dots in a chitosan film to obtained a sensor for norfloxacin (NOR) in the presence of dopamine, caffeine, and uric acid. The morphological, structural and electrochemical characteristics of the nanostructured material were evaluated using spectrophotometry, X-ray diffraction, transmission electronic microscopy and voltammetry. The high electrochemical activity, fast electron transfer rate and high surface area enhanced the oxidation peak currents and shifted the peak potentials of NOR for more negative values (typically at 0.95 V vs. Ag/AgCl). Electrochemical determination of NOR was carried out using square-wave adsorptive anodic stripping voltammetry (SWAdASV). Response is linear in the 0.2 to 7.4 μmol L^-1 NOR concentration range, and the detection limit is as low as 6.6 nmol L^-1. The method was successfully applied to the determination of norfloxacin in pharmaceutical formulation, synthetic urine and spiked serum. Graphical abstract Schematic presentation of a voltammetric method using a glassy carbon electrode modified with carbon black and CdTe quantum dots in a chitosan film for the determination of norfloxacin in serum and urine samples.