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Voltammetric Determination of Warfarin at a Screen-Printed Carbon Electrode
Žužičová, Victória ; Vyskočil, Vlastimil (advisor) ; Dejmková, Hana (referee)
In this Bachelor Thesis, the electrochemical behaviour of the drug warfarin sodium was studied at a screen-printed carbon electrode (SPCE) using DC voltammetry (DCV) and differential pulse voltammetry (DPV). The dependence of the voltammetric behaviour of the substance on the pH of the medium was studied in Britton-Robinson buffer (BR buffer) in the pH range of 2.0−12.0. A pH of 7.0 was chosen as the optimum pH for both voltammetric techniques. A repeatability of 3.8% for DCV and 4.3% for DPV was determined for the selected pH. Calibration dependence was monitored under the selected optimal conditions in the concentration range 2∙10−6 to 1∙10−4 mol∙dm−3 . The limit of detection (LOD) was determined to be 1.05∙10−6 mol∙dm−3 for DCV and 2.59∙10−7 mol∙dm−3 for DPV. The limit of quantification (LOQ) was 3.50∙10−6 mol∙dm−3 for DCV and 8.62∙10−7 mol∙dm−3 for DPV. These newly developed methods were used for the determination of the active ingredient in the pharmaceutical formulation Warfarin Orion 5 mg. The values measured by voltammetric methods were compared with those obtained by spectrophotometric measurements. Key words Electrochemistry, Warfarin, Anticoagulants, Direct Current Voltammetry, Differential Pulse Voltammetry, Screen-Printed Carbon Electrode
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Study of electrochemical behaviour of quinine and cinchonidine at boron doped diamond electrode
Brunovská, Veronika ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
In this thesis, it was for the first time studied the electrochemical behaviour of cinchona alkaloids quinine and cinchonidine by cyclic voltammetry and differential pulse voltammetry using boron doped diamond (BDD) thin film as an electrode material. Cyclic voltammograms did not exhibit any significant anodic signals corresponding to a simple electrode reaction. However, current increase with indistinctive maxima compared to the basic electrolyte was recorded in Britton - Robinson buffers with pH 2,0 − 12,0 medium. Accordingly, insignificant signals observable in the cathodic area at far negative potential close to the potential of decomposition of the supporting electrolyte , presumably to the reduction of quinoline skeleton. It was found by means of differential pulse voltammetry that the number of those observable current maxima varies for quinine and cinchonidine in different supporting electrolytes. Quinine provided the best developed anodic peaks in the medium of BR buffer pH 5,0 and 6,0 and cinchonidine in pH 7,0, 9,0 and 12,0. The calibration dependence of anodic peak of quinine in BR buffer pH 5,0 is linear in the concentration range 6∙10−6 mol∙l−1 − 1∙10−4 mol∙l−1 with limit of quantitation 4,39∙10−6 mol∙l−1 . In the cathodic area the limit of quantitation is 4,33∙10−5 mol∙l-1 . The...
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