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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 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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Polarographic and Voltammetric Determination of Fomesafen
Maška, Jan ; Barek, Jiří (advisor) ; Fischer, Jan (referee)
The work is related to the polarographic and voltammetric determination of Fomesafen on the basis of its cathodic reduction using classical dropping mercury electrode (DME), hanging mercury drop electrode (HMDE) and non-traditional mercury meniscus modified silver solid amalgam electrode (m-AgSAE). Silver solid electrode (AgSAE) was developed as an alternative to mercury electrodes regarding legislative complications limitating usage of mercury because of its supposed toxicity. Properties of this electrode are very similar to the ones of mercury electrodes, mainly outstandingly broad cathodic potential region but excelent sensitivity either. As an electrode material, silver amalgam was used which non-toxicity is obvious given for example even by its long-term usage in stomatology as a main item for production of tooth-fillings. For model determination, Fomesafen was chosen because of its previous and sometimes also present usage as a major component of herbicid agents in agriculture. Its factual toxicity was actually proven and it was also classified as a potential carcinogen for humans. Historically, its usage was relatively deliberately massive, significant was e.g. in USA, but presently it was already forbidden in many countries. The intention of the work was to compare the analytical qualities...
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Electrochemical Biosensors and Detectors Based on Silver Solid Amalgam for Analysis in Flow Systems
Josypčuk, Oksana ; Barek, Jiří (advisor) ; Vytřas, Karel (referee) ; Ludvík, Jiří (referee)
In this Ph.D. thesis new possibilities of using amalgam electrodes are presented. First of all, the tubular detector based on silver solid amalgam (TD-AgSA) was designed for determination of reducible compounds in flow systems. It was tested on model solutions of Cd2+ , Zn2+ and 4-nitrophenol in amperometric mode under conditions of flow injection analysis. Results have shown that developed tubular detector is simple and low cost device suitable for detection of reducible compounds with good sensitivity, repeatability and long-term stability (at least 2 years) with possibility to work at potentials up to 2 V in aqueous solutions. Afterwards, this newly developed detector was successfully used for the determination of an active ingredient lomustine in pharmaceutical preparation CeeNU® Lomustine by non-stop-flow differential pulse voltammetry based on reduction of present nitroso group. For measurements in the flow system miniature reference electrodes saturated calomel electrode, mercury-mercurous sulfate, and mercury-mercuric oxide electrode based on paste silver solid amalgam were fabricated and tested for 14 months. The calomel electrode based on paste silver amalgam proved to be the most resistant to polarization and it was used in all experiments in this thesis. Next, the electrochemical...
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