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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 and amperometric determination of 5-nitroquinoline in drinking and river water using carbon film electrode
Rumlová, Tereza ; Barek, Jiří (advisor) ; Dejmková, Hana (referee)
This work focuses on optimization and application of voltammetric methods for determination of 5-nitroquinoline in model samples of drinking and river water using carbon film electrode (CFE). The advantages of carbon film electrode are primarily its wide potential window in both cathodic and anodic regions and also low environmental stress compared to mercury electrodes. In this contribution, CV and AdSV were used to observe electrochemical processes. For determination of 5-nitroquinoline DPV and FIA were used. Solid phase extraction was investigated as a method for preliminary separation and preconcentration for DPV. Determination of 5-nitroquinoline at CFE is based on cathodic reduction of nitrogroup. This work demonstrates the application of carbon film electrode for determination of 5-nitroquinoline in submicromolar concentrations in model samples of water.
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Voltammetric and amperometric detection of genotoxic pyrene derivatives at boron-doped diamond film electrode
Yosypchuk, Oksana ; Barek, Jiří (advisor) ; Nesměrák, Karel (referee)
This thesis is concentrated on the optimization of conditions for determination of genotoxic environmental pollutants whitch belong to derivatives of polycyclic aromatic hydrocarbons − 1-nitropyrene (1-NP), 1-aminopyrene (1-AP) and 1-hydroxypyrene (1-HP). All three compounds were determined by differential pulse voltammetry (DPV) at boron-doped diamond film electrode in water-methanolic solutions. Further, 1-AP and 1-HP were determined in a model sample of urine. For this purpose, effective separative techniques such as solid phase extraction and high performance liquid chromatography with reverse phase and amperometric detection at above mentioned type of electrode were used. Limits of detection of all tested compounds in water-methanolic solutions are 9⋅10−8 −3⋅10−7 mol dm−3 using DPV and 1⋅10−8 mol dm−3 for 1-HP and 1-AP in model sample of urine determined by HPLC with amperometric detection.
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Voltammetric Determination of Anticancer Drug Flutamide and Its Metabolite 4-Nitro-3-trifluoromethylaniline
Radová, Jitka ; Barek, Jiří (advisor) ; Dejmková, Hana (referee)
The subject of this Diploma Thesis has been the study of electrochemical behavior of anticancer drug flutamide (FLD) and one of its metabolites 4-nitro-3-trifluoromethylaniline (NTMA). The aim was to find and define the optimum conditions for the determination of both compounds at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and at a carbon film electrode (CFE) using DC voltammetry (DCV) and differential pulse voltammetry (DPV). This Diploma Thesis follows closely the Bachelor Thesis, defended at the Department of Analytical Chemistry, Faculty of Science, Charles University in Prague. In this Bachelor Thesis, a voltammetric determination of FLD using DCV and DPV at m-AgSAE has been described, with attained limits of quantification (LQs) 5.0·10-6 mol.dm-3 (for DCV) and 3.0·10-6 mol.dm-3 (for DPV). In presented Diploma Thesis, voltammetric behavior of NTMA has been studied in dependence on the pH of the medium of Britton-Robinson (BR) buffer-methanol (9:1). The optimum conditions have been found for the determination of this substance using DCV and DPV at m-AgSAE and CFE in the cathodic area. As the optimum media, BR buffer-methanol (9:1) of resulting pHf 8.3 (for both DCV and DPV at m-AgSAE) and of pHf 5.1 (for both DCV and DPV at CFE) have been chosen. Further, the LQs have...
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New Electrochemical Methods for Determination of Nitro and Oxo Derivatives of Fluorene
Vyskočil, Vlastimil ; Barek, Jiří (advisor) ; Ludvík, Jiří (referee) ; Heyrovský, Michal (referee)
4. Conclusion This Thesis represents a contribution to the search for new analytical methods applicable on environmental and biological samples. The current state- of-art concerning the formation, occurrence, and biological activity of fluorene and its nitro and oxo derivatives was summarized in Chapter 1. Further experimental work was focused on assessment of new approaches in the detection of the studied compounds. Attention was paid mainly to nitrofluorenes, fluorenone and nitrofluorenones, namely 2-nitrofluorene, 2,7-dinitrofluorene, 9-fluorenone, 2-nitro-9-fluorenone, and 2,7-dinitro-9- fluorenone and the possibilities of their determination using polarographic and voltammetric methods. Interactions of calf thymus dsDNA with 2-nitrofluorene and 2,7-dinitrofluorene at the DNA/SPCPE were investigated and subtle DNA damage under conditions of direct DNA-analyte interaction at room temperature and damage to DNA bases under condition of electrogeneration of short-lived radicals of nitrofluorenes at human body temperature were found. The obtained results can be summarized as follows: ● Modern polarographic and voltammetric methods at mercury electrodes developed for determination of trace amounts of 9-fluorenone and 2,7-dinitro-9-fluorenone (and other NPAHs generally) in concentration ranges from 2×10-8 to...
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