Sulfamethoxazole (SMX) is one of the most used antibiotics, and its concentration in the environment is increasing, which is raising concerns about the development of bacterial resistance. At the same time, the continuous presence of antibiotics in water results in adverse effects on human health. Conventional analytical methods for the determination of antibiotics in aqueous media are mainly based on chromatographic techniques. However, recent developments have focused on faster, more cost-effective, and portable analytical approaches, among which the electrochemical sensors have become increasingly prominent. In present master's thesis, an electrochemical sensor for the determination of SMX was developed based on a screen-printed electrode (SPE) with a carbon working electrode modified with a conductive polymer and an additional carbon material.
The first part presents a comparison between two types of carbon-based electrodes: a screen-printed electrode with a carbon working electrode (SPE-C) and a screen-printed electrode with a single-walled carbon nanotube working electrode (SPE-SWCNT). Both electrodes were modified using conductive polymers, carbon nanomaterials, and metal oxide nanomaterials. The modification based on a combination of polymethylene blue and carbon quantum dots exhibited the best response. In the second part, the modified electrode was used to investigate the electrochemical properties of the system and to construct a calibration curve, from which the limit of quantification (0.1 μM) and the limit of detection (0.06 μM) were determined. In the third part, the electrochemical determination is compared with high-performance liquid chromatography (HPLC), demonstrating that both techniques provide comparable results for the determination of low SMX concentrations (down to 0.1 μM).
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