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Voltammetric Determination of Nimesulide at a Polished Silver Solid Amalgam Electrode
Koščová, Kristína ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
This bachelor thesis focuses on investigating the electrochemical behavior of the substance nimesulide. The stability of the stock solution was monitored using UV-VIS spectrophotometry. A solid silver amalgam electrode with a polished surface was chosen as the working electrode, a silver chloride reference electrode (3M KCl), and a platinum auxiliary electrode were used. For the techniques of DC voltammetry (DCV) and differential pulse voltammetry (DPV), optimal conditions for the determination of nimesulide were sought (optimal pH, range of regenerative potentials). The calibration dependence was measured in concentration ranges of 10−7 , 10−6 , and 10−5 mol/L. In the case of DCV, a linear calibration dependence was achieved in the concentration range of 1-100 μmol/L (with a limit of detection (LD) ≈ 0.27 μmol/L and with a limit of quantification (LQ) ≈ 0.91 μmol/L). In the case of DPV, linearity was achieved in the range of 4-100 μmol/L (LD ≈ 0.60 μmol/L and LQ ≈ 2.0 μmol/L). The developed voltammetric methods were used to determine nimesulide in drinking and well water and in pharmaceutical forms of Nimesil 100 mg and Aulin 100 mg.
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Voltammetric Determination of 8-Hydroxy-5-nitroquinoline on a Silver Solid Amalgam Electrode
Bartůňková, Erika ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
This Bachelor Thesis is dedicated to the study of the electrochemically active substance 8-hydroxy-5-nitroquinoline. The stability of the prepared standard solution was monitored by UV/VIS spectrometry throughout the electrochemical measurements. A polished silver solid amalgam electrode was chosen as the working electrode. First, the optimum conditions for the measurements were determined by DC voltammetry and differential pulse voltammetry. The calibration dependence was subsequentlymeasuredbybothtechniquesintheconcentrationrangefrom1·10−7 to 1·10−5 mol/L. The DC voltammetry method was also used to measure the calibration dependence in model matrices of drinking and well water in the concetration order of 10−6 mol/L. To further investigate the electrochemical processes and controlling processes in the electrochemical transformation of 8-hydroxy-5-nitroquinoline, the cyclic voltammetry technique was used and applied at different polarization rates.
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Voltammetric Determination of Genotoxic Nitrobiphenyls
Horáková, Eva ; Vyskočil, Vlastimil (advisor) ; Navrátil, Tomáš (referee)
The presented diploma thesis is devoted to study of determination of 4-nitrobiphenyl (4-NBP) in model river water by DC voltammetry (DCV) and differential pulse voltammetry (DPV) at m-AgSAE (diploma thesis relates to bachelor thesis, in it DCV and DPV methods for determination of 4-NBP in deionized water were developed). Limit of determination (LOD) is 2·10-7 mol·l-1 by DCV and 4·10-7 mol·l-1 by DPV. The adsorptive stripping DPV (AdSDPV) technique was tested to archive lower LOD the AdSDPV, optimal conditions were not found. Electrochemical behavior of 2-nitrobiphenyl (2-NBP) at m-AgSAE was studied. Optimal conditions for its determination by both techniques DCV and DPV were found in methanol-0,01 mol·l-1 LiOH (1:9) and in this medium peak current dependence in 1·10-7 mol·l-1 to 1·10-4 mol·l-1 2-NBP (LOD ≈ 2·10-7 mol·l-1 by DCV and 1·10-7 mol·l-1 by DPV) concentration range was measured. Developed methods were successfully tested for determination of 2-NBP in drinking and river water samples. For both mediums obtained LODs were 2·10-7 mol·l-1 by DCV and 1·10-7 mol·l-1 by DPV. AdSDPV technique was unsuccessfully tested to achieve lower LOD. Optimal conditions for simultaneous determination of 4-NBP and 2-NBP by DPV technique at m-AgSAE were found: methanol-0,25 mol·l-1 acetate buffer (pH = 6,0) 3:7....
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Voltammetric Determination of Dinitronaphthalenes Using Single Crystal Silver Amalgam Electrode
Tvrdíková, Jana ; Barek, Jiří (advisor) ; Dejmková, Hana (referee)
Voltammetric methods for determination of 1,3-dinitronaphthalene (1,3-DNN), 1,5-dinitronaphthalene (1,5-DNN) and 1,8-dinitronaphthalene (1,8-DNN) using DC voltammetry (DCV) and differential pulse voltammetry (DPV) at novel single crystal silver amalgam electrode (CAgAE) were developed in this work. Developed methods may be used for determination of 1,3-DNN within a concentration range 2 - 10 μmol.L-1 with LoQ 2 μmol.L-1 using DCV and 1 - 100 μmol.L-1 with LoQ 1 μmol.L-1 by DPV; 1,5-DNN wihin a concentration range 2 - 10 μmol.L-1 with LoQ 2 μmol.L-1 using DCV and 1 - 10 μmol.L-1 with LoQ 1 μmol.L-1 by DPV and 1,8-DNN within a concentration range 2 - 10 μmol.L-1 with LoQ 2 μmol.L-1 using DCV and 0,3 - 1 μmol.L-1 with LoQ 0,3 μmol.L-1 by DPV. An attepmt to decrease LoQ by adsorptive stripping differential pulse voltammetry was not successful. Process of electrochemical reduction of selected dinitronaphthalenes on the working electrode was also studied by cyclic voltammetry. This work verified the use of CAgAE as alternative electrode material to mercury electrodes for determination of electrochemically reducible organic compounds in aqueous-methanolic media. Small dimensions of the CAgAE are the main advantages which predetermine its use in voltammetric microvolume batch analysis and amperometric detection in...
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Voltammetric Determination of 5-Nitrobenzimidazole Using Non-Traditional Electrode Materials
Chládková, Barbora ; Vyskočil, Vlastimil (advisor) ; Zima, Jiří (referee)
5 Abstract This Diploma Thesis is targeted on the determination of 5-nitrobenzimidazole (5-NBIA) using following techniques: DC voltammetry (DCV) and differential pulse voltammetry (DPV). As working electrodes, a silver amalgam paste electrode (AgA-PE), which was constructed for this determination in the form of a new prototype, a bismuth film electrode (BiFE), at which the optimum conditions for the deposition of the bismuth film at a suitable substrate (glassy carbon electrode and gold electrode were tested for this purpose) were initially optimized, and a glassy carbon electrode (GCE) were used. The optimum conditions for the voltammetric determination of 5-NBIA at the AgA-PE (in a medium of Britton-Robinson buffer (BR-buffer) of pH 7.0 for both DCV and DPV), at the BiFE with gold substrate (BR-buffer of pH 9.0 for both DCV and DPV; the film was deposited "ex situ" in a stirred plating solution (1000 mg L-1 Bi(III) solution in 0.1 mol L-1 acetate buffer of pH 4.5) for 300 s), and at the GCE (BR-buffer of pH 5,0 for both DCV and DPV). Under these conditions, calibration dependences were measured in the concentration ranges of 0.1 - 100 µmol L-1 (pro DCV a DPV na AgA-PE) and 1 - 100 µmol L-1 (pro DCV a DPV na BiFE a GCE), and the limits of quantification (LQs) were calculated for particular methods: LQ ≈...
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Voltammetric Determination of 5-Nitroimidazole - The Structural Unit of Nitroimidazole Drugs
Šmídková, Monika ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
Presented Diploma Thesis deals with the study of electrochemical behavior of 5-nitroimidazole (5-NI), with the search for optimal conditions for its determination using techniques of DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and at a boron-doped diamond film electrode (BDDFE), and with the comparison of reached limits of quantification (LQs). The optimal conditions found for measuring calibration dependences of 5-NI at the m-AgSAE in deionized water were as follows: Britton-Robinson buffer of pH 7.0 and 10.0 for DCV and DPV, respectively. At both thechniques, it is advisable to use an electrochemical regeneration of the electrode surface by the application of a couple of regeneration potentials Ereg,1 = 0 mV and Ereg,2 = −800 mV. The calibration dependences were measured in the concentration range from 1·10−6 to 1·10−4 mol·l−1 , with the LQs of 1.0·10−6 mol·l−1 for DCV at the m-AgSAE and 1.5·10−6 mol·l−1 for DPV at the m-AgSAE. The concentration dependences of 5-NI at the BDDFE were measured using the DCV technique in the BR buffer of pH 3.0. For the DPV technique, the optimal medium seemed to be the BR buffer of pH 2.0, however, because of the presence of an interfering peak in the supporting electrolyte,...
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Large-Surface Carbon Film Electrode - A Novel Sensor for Voltammetric Determination of Electrochemically Oxidizable Organic Compounds
Šmejkalová, Hana ; Vyskočil, Vlastimil (advisor) ; Dejmková, Hana (referee)
of the Diploma Thesis In this Diploma Thesis, the electrochemical behavior of 4-nitrophenol (4-NP) was studied at a newly prepared large-surface carbon film electrode (ls-CFE) using techniques of DC voltammetry (DCV) and differential pulse voltammetry (DPV) with the aim to develop sensitive analytical methods for its determination. Voltammetric behavior of 4-NP was investigated in the region of anodic potentials, in dependence on the pH of the medium used (realized using Britton-Robinson buffer). The optimum pH values for the determination of 4-NP were chosen as follows: pH 3.0 (for DCV) and pH 7.0 (for DPV). During anodic oxidation of 4-NP on the ls-CFE at the concentration of the analyte of 1·10-4 mol/l, the passivation of the electrode surface occurred. Thus, it was decided to record series of measurements always at a new carbon film. Using the sample of 4-NP (at the concentration of 1·10-4 mol/l), the repeatability of the application of individual carbon films was tested, with obtained RSD values of 3.7% and 3.6% for DCV and DPV, respectively. Under optimum conditions, the calibration dependences of 4-NP were measured in the concentration range from 1·10-6 to 1·10-4 mol/l, with the limits of quantification (LQs) of 1.5·10-6 mol/l (for DCV at the ls-CFE) and 4.6·10-7 mol/l (for DPV at the...
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Voltammetric Determination of Genotoxic 6-Nitrochrysene at a Mercury Meniscus Modified Silver Solid Amalgam Electrode
Šmídková, Monika ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
This Bachelor Thesis is devoted to the study of electrochemical behavior of 6-nitrochrysene (6-NCH) and to the finding of the optimum conditions for its determination using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE). For measuring the concentration dependences of 6-NCH, the optimum medium methanol - BR buffer pH 9.0 (1:1) and the proper regeneration potentials Ereg,1 = 0 mV, Ereg,2 = -600 mV have been chosen for DCV at m-AgSAE and the medium methanol - BR buffer pH 10.0 (1:1) and the proper regeneration potentials Ereg,1 = 0 mV, Ereg,2 = -750 mV have been chosen for DPV at m-AgSAE. The concentration dependence was found to be linear only for the lowest concentration range of 10-7 mol·l-1 . In the concentration range of 10-6 mol·l-1 , the concentration dependences observed were polynomial. This result indicates a possible adsorption of 6-NCH on the surface of working electrode. Reached limits of quantification (LQ) were 1·10-7 mol·l-1 for DCV at m-AgSAE and 5·10-8 mol·l-1 for DPV at m-AgSAE. For comparison, the concentration dependence of 6-NCH was measured in methanol using UV-VIS spectrophotometry. Reached LQ ~ 1·10-7 mol·l-1 is comparable with LQs reached using DCV and DPV techniques.
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