Use of nanostructured conductive polymers for the electrochemical determination of metronidazole

In this study, it is aimed to develop a modified electrode with nanostructured conductive polymers for the electrochemical determination of metronidazole (MNZ) active drug substance, which is used in the treatment of many infections. For this purpose, pencil graphite electrodes (PGE) were modified with over-oxidized nanofiber structured poly(3,4-ethylenedioxythiophene) (OxPEDOTNF) and polypyrrole (OxPPyNF) by electropolymerization method. The performances of the prepared PGE/OxPEDOTNF and PGE/OxPPyNF electrodes were investigated for MNZ by the differential pulse voltammetry method. In addition, the electrochemical signals of nanofiber and non-nanofiber electrodes for MNZ were determined. Surface morphology of the modified electrodes was determined by scanning electron microscopy (SEM) and electrochemical characterization was determined by cyclic voltammetry. It was determined that the response of the PGE/OxPEDOTNF electrode to MNZ was linear in the concentration range of 10-200 µM, and the PGE/OxPPyNF electrode was linear in the concentration range of 5-500 µM. The limit of detection (LOD) for PGE/OxPEDOTNF in MNZ determination was calculated as 2.76 µM and the limit of qantification (LOQ) was calculated as 9.2 µM. The LOD for PGE/OxPPyNF in MNZ determination was calculated as 3.8 µM and the LOQ was calculated as 12.8 µM. In addition, the performance of these modified electrodes in real samples was tested for drug tablets containing MNZ. In this study, it was found that nanofiber structured electrodes performed better than PGE and non-nanofiber structured electrodes, and overoxidized electrodes performed better than non-overoxidized electrodes. Although PGE/OxPEDOTNF has a longer lifetime and lower detection limit than PGE/OxPPyNF, PGE/OxPPyNF has better repeatability and a wider linear operating range. In addition, the optimum working pH for PGE/OxPPyNF is 8,0 and therefore, it offers the opportunity to work in conditions close to the pH value of body fluids. In this thesis study, it was determined that the performance of PGE/OxPPyNF in electrochemical determinations of MNZ was better than PGE/Ox/PEDOTNF. However, both modified electrodes can be used successfully for MNZ determinations.