Development of a modified electrode based voltammetric method for chloramphenicol determination

In this thesis, a voltammetric method based on modified electrodes was developed for the determination of chloramphenicol (CAP), a broad-spectrum antibiotic. The study is structured in two main parts according to the type of modification applied to the glassy carbon electrode. In the first part, graphene oxide (EEGO) was synthesized via the electrochemical exfoliation method and employed for electrode surface modification. The prepared electrode was characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and X-ray diffraction (XRD). Differential pulse voltammetry (DPV) measurements revealed a linear response for CAP in the concentration range of 1,0–62,5 µM with a detection limit of 0,0673 µM. Recovery studies conducted in real samples such as milk and honey demonstrated satisfactory accuracy, with recoveries ranging between 84.88% and 109.48%. In the second part of the study, graphene oxide synthesized by the Hummer's method was combined with polystyrene-4-sulfonate (PSS) in specific ratios and reduced using hydrazine monohydrate to obtain a reduced graphene oxide–polystyrene-4- sulfonate (PSS-rGO) composite. The resulting modified electrode was similarly characterized and applied for CAP determination in real samples. The developed sensor exhibited a linear range of 2,5–112,5 µM and a detection limit of 0,8329 µM. Recovery values obtained from milk and honey samples ranged from 77.56% to 83.12%