Rising amounts of antibiotic residues in wastewater cause serious problems including increased bacterial resistance. Wastewater treatment plants (WWTPs) do not, in the case of new, modern pharmaceuticals, ensure their complete removal. Ciprofloxacin (CIP) is one of many micropollutants that partially pass through WWTPs, implying that its monitoring is essential for the assessment of the water quality. In real sewage systems, the determination of CIP needs to be performed under flowing conditions, which calls for the deployment of inexpensive, robust, and easily integrable approaches such as electrochemical techniques. However, to the best of our knowledge, there is no report on the electrochemical determination of CIP in a flowing matrix. To bridge this gap, we perform here cyclic and square-wave voltammetric sensing study of CIP employing boron-doped diamond screen printed electrodes in a custom-made 3D printed flow-through cell to mimic conditions in real sewage systems. An irreversible two-step oxidation of CIP is demonstrated, with the first step providing clear Faradaic response as analytically relevant signal. This response was found to scale with the sample flow rate according to the prediction given by Levich equation. Our work provides an in-depth inspection of the electrochemical response of CIP under controlled-convection conditions, which is an essential prerequisite for monitoring this antibiotic in real flowing sewage systems.

Department of Inorganic Materials Faculty of Chemical and Food Technology Slovak University of Technology in Bratislava Radlinského 9 821 37 Bratislava Slovakia

Department of Inorganic Technology Faculty of Chemical and Food Technology Slovak University of Technology in Bratislava Radlinského 9 821 37 Bratislava Slovakia

Department of Physical Chemistry Faculty of Chemistry University of Bialystok Ciolkowskiego 1K 15 245 Białystok Poland

Institute of Analytical Chemistry Faculty of Chemical and Food Technology Slovak University of Technology in Bratislava Radlinského 9 821 37 Bratislava Slovakia

J Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 2155 3 18223 Prague Czech Republic

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