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This work is focused on the homemade screen-printed carbon paste electrode containing basically graphite powder (or glassy carbon powder), poly(vinylbchloride) (PVC) and paraffin oil. It compares the electrochemical properties of conventional carbon-based electrodes and prepared screen-printed carbon paste electrodes towards [Fe(CN)6]3-/[Fe(CN)6]4- and quinone/hydroquinone redox couples. Significant attention is paid to the development of the corresponding carbon inks, printing and the surface characterisation of the resulting electrodes by the scanning electron microscopy. An optimization consisted of the selection of the organic solvent, the optimal content of the used polymer with the chosen paste binder, appropriate isolation of electric contact, etc. Very similar properties of the prepared screen-printed electrodes, containing only corresponding carbon powder and 3 % PVC, with their conventional carbon paste electrode and glassy carbon-based electrodes, were observed during their characterisation. Screen-printed electrodes, with the pasting liquid usually provided satisfactory analytical data. Moreover, they can be used in the flow injection analysis and could undoubtedly replace the carbon paste grooved electrodes. It can be assumed that certain progress in the development of electrode materials was achieved by this research.

The present work introduced copper oxide nanoparticles as an efficient electrode modifier for sensitive adsorptive differential pulse voltammetric assaying of marbofloxacin (MRB) in pharmaceutical formulations and surface water samples. In the presence of sodium dodecyl sulphate (SDS) at pH 4.0, the marbofloxacin molecule was irreversibly oxidized at the electrode surface showing an anodic oxidation peak at 0.954 V. The electrode reaction mechanism was assumed as adsorption‐reaction controlled accompanied by the transferring of two electrons and proton exchange in agreement with the molecular orbital calculations performed on MRB molecule suggesting the oxidation of the amino group in the piperazinyl ring. At the optimized measuring conditions, the recorded peak heights were linearly correlated with the MRB concentration within the range from 6.67 to 360 ng mL−1, and the estimated LOD value was 2.2 ng mL−1. The integrated sensor showed a prolonged operational lifetime with good reproducibility of measurements. Based on the selectivity and sensitivity of the proposed method, MRB was successfully assayed in pharmaceutical formulations and surface water samples with mean average recoveries agreeable with the official method. [ABSTRACT FROM AUTHOR]

Nanostructured ZrO2‐based materials with their biocompatibility, excellent electrical, and surface charge properties became one of the best candidates for the electrochemical sensing applications. Here, synthesis of Zr1‐xCuxLaxO2 compounds was achieved in nanoscale and fully characterized using XRD, TEM, DRS, and cyclic voltammetry. A mixture of monoclinic and cubic phases was detected for the undoped ZrO2 (Z sample, x = 0). For the Cu‐doped compounds, (ZFW1, x = 0.05 and ZFW2, x = 0.1), a combination of cubic fluorite and monoclinic phase were detected. The intensity of the monoclinic phase for the Cu‐doped was higher than that of the undoped ZrO2 sample. Cu and La co‐doped samples (ZL1C1, x = 0.05 and ZL2C2, x = 0.1) were stabilized in a single cubic phase structure. Therefore, their band gap dropped from (4.8 eV) for the undoped ZrO2 to (1.49 eV) for the ZL1C1 sample and (2 eV) for the ZL2C2 sample. Voltammetric sensing of neurotransmitter metabolites (vanillylmandelic acid (VMA) and homovanillic acid (HVA)) was achieved using the modified electrodes due to their acquired high electrocatalytic and high electrochemical performance. [ABSTRACT FROM AUTHOR]