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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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Voltammetric Determination of 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol on a Screen-Printed Carbon Electrode
Jančová, Jana ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
The aim of the presented Master Thesis was to study an electrochemical behaviour of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) resulting in the founding of optimum conditions for their voltammetric determination at a screen-printed carbon electrode (SPCE) using DC voltammetry (DCV) and differential pulse voltammetry (DPV). Voltammetric behaviour of both compounds was investigated in dependence on the pH of the medium (realized using Britton-Robinson buffer). The optimum pH for the voltammetric determination of 2,4-D on the SPCE was chosen to be pH 5,0 for both voltammetric techniques, and, for 2,4-DCP, it was chosen to be pH 6,0 for both voltammetric techniques. The determination of 2,4-D at a concentration of 1·10-4 μmol·L-1 showed good repeatability for both voltammetric techniques used (1.3% for DCV and 0.7% for DPV), and, for 2,4-DCP, it showed acceptable repeatability for both voltammetric techniques used (1.3% for DCV and 4.8% DPV). Under optimum conditions, the calibration dependence of 2,4-D was measured for DCV in the concentration range of 10-100 μmol·L-1 , with limit of quantification (LOQ) of 1.0 μmol·L-1 and limit of detection (LOD) 0.3 μmol·L-1 . Under optimum conditions, the calibration dependence of 2,4-D was measured for DPV in the concentration range...
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Voltametric Determination of 4-Nitrophenol at a Bismuth Film Electrode
Hausner, Jiří ; Barek, Jiří (advisor) ; Dejmková, Hana (referee)
This Bachelor Thesis is focussed on the study of electrochemical behaviour of 4-nitrophenol (4-NP) and the search for optimal conditions for its voltammetric determination at a bismuth film-modified gold electrode (BiF-AuE). Voltammetric behaviour of 4-NP (c = 1×10-4 mol L-1 ) was investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) in dependence on the pH of the medium used (Britton-Robinson buffers). For both techniques, Britton-Robinson buffer of pH 7.0 was chosen as the optimum medium. Repeatability of the determination of 4-NP (c = 1×10-4 mol L-1 ) was 0.6 % and 0.9 % for DCV and DPV, respectively. Calibration dependences of 4-NP were measured in the concentration range from 1×10-6 to 1×10-4 mol L-1 under the optimum conditions. Attained limits of quantification (LQs) were 7.6×10-7 mol L-1 and 1.5×10-6 mol L-1 for DCV and DPV, respectively. The applicability of the newly developed voltammetric methods for the determination of 4-NP was verified on model samples of drinking water with LQ 7.5×10-6 mol L-1 for DCV at the BiF-AuE and 1.4×10-6 mol L-1 for DPV at the BiF-AuE.
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Voltametric Determination of 4-Nitrophenol at a Bismuth Film Electrode
Hausner, Jiří ; Barek, Jiří (advisor) ; Dejmková, Hana (referee)
This Bachelor Thesis is focussed on the study of electrochemical behaviour of 4-nitrophenol (4-NP) and the search for optimal conditions for its voltammetric determination at a bismuth film-modified gold electrode (BiF-AuE). Voltammetric behaviour of 4-NP (c = 1×10-4 mol L-1 ) was investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) in dependence on the pH of the medium used (Britton-Robinson buffers). For both techniques, Britton-Robinson buffer of pH 7.0 was chosen as the optimum medium. Repeatability of the determination of 4-NP (c = 1×10-4 mol L-1 ) was 0.6 % and 0.9 % for DCV and DPV, respectively. Calibration dependences of 4-NP were measured in the concentration range from 1×10-6 to 1×10-4 mol L-1 under the optimum conditions. Attained limits of quantification (LQs) were 7.6×10-7 mol L-1 and 1.5×10-6 mol L-1 for DCV and DPV, respectively. The applicability of the newly developed voltammetric methods for the determination of 4-NP was verified on model samples of drinking water with LQ 7.5×10-6 mol L-1 for DCV at the BiF-AuE and 1.4×10-6 mol L-1 for DPV at the BiF-AuE.
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Voltammetric Determination of Herbicide Aclonifen Using Mercury Electrodes
Murcková, Klára ; Vyskočil, Vlastimil (advisor) ; Dejmková, Hana (referee)
Presented Diploma Thesis is focused on electroanalytical determination of the herbicide Aclonifen, which belongs to a group of herbicides derived from diphenylether. These herbicides are used due to their effects - inhibition of protoporfyrinogen oxidase synthesis and also inhibition of biosynthesis of carotenoids. Due to its widespread use in agricultural, toxical effects on humans and because of its negative impacts particularly on aquatic ecosystems there is a need for methods capable of determining the presence of Aclonifen in the environment to monitor its ecological impacts. Optimal conditions for the determination of Aclonifen have been investigated in BR buffer - methanolic solution and in BR buffer. Electrochemical behavior of the substance has been studied using direct current voltammetry (DCV), differential pulse voltammetry (DPP) and adsorptive stripping voltammetry (AdSV) on the hanging mercury drop electrode (HMDE) and by using TAST polarography and differential pulse polarography (DPP) on the dropping mercury electrode (DME). UV/VIS spectrophotometric detection was used for comparison to electrochemical detection. Used wavelengths were 308 nm and 388 nm. For electrochemical determination of Aclonifen the above mentioned techniques were used and following results were obtained: DCV...
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Voltammetric Determination of 4-Nitrophenol at a Large-Surface Carbon Film Electrode
Šmejkalová, Hana ; Vyskočil, Vlastimil (advisor) ; Dejmková, Hana (referee)
The aim of presented Bachelor Thesis was to study an electrochemical behavior of 4-nitrophenol (4-NP) resulting in the founding of optimum conditions for its determination at newly prepared large-surface carbon film electrode (ls-CFE) using DC voltametry (DCV) and differential pulse voltammetry (DPV). Voltammetic behavior of 4-NP was investigated in dependence on the pH of the medium (realized using Britton-Robinson buffer). As optimum pH values for voltammetric determination of 4-NP at ls-CFE in cathodic potentials region, the pH values 6.0 (for DCV) and 7.0 (for DPV) were chosen. The determinations of 4-NP at ls-CFE (at a concentration of the analyte of 1·10-4 mol/l) showed a good repeatability for both voltammetric techniques used (2.2 % for DCV and 0.4 % for DPV). Therefore, the possibility of an electrochemical regeneration of the electrode surface has not been further investigated. Under optimum conditions, the calibration dependences of 4-NP were measured in the concentration range from 2·10-6 to 1·10-4 mol/l, with limits of quantification (LQ) of 2.3·10-6 mol/l (for DCV at ls-CFE) and 1.8·10-6 mol/l (for DPV at ls-CFE). The applicability of the newly developed methods of the determination of 4-NP was verified on the model samples of drinking water, with LQ of 1.0·10-6 mol/l (for DCV at...
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