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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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The Use of Chemically Modified Electrodes in Voltammetric Analysis of Nitroaromatic Compounds
Prchal, Vít ; Vyskočil, Vlastimil (advisor) ; Navrátil, Tomáš (referee)
The main objective of this Diploma Thesis is studying the possibility of detection of nitro derivatives of aromatic hydrocarbons by using chemically modified working electrodes in electrochemical analysis. Compounds analyzed in this work were 1-nitronaphthalene and 6- nitrochrysene - these compounds were chosen on previous experience with surface modified working electrodes (the chemical/physical properties of these substances). All the analyses were performed by using differential pulse voltammetry (DPV) on hanging mercury drop electrode (HMDE) in classic three-electrode system. The original premise of chemical modification of electrode surface is the change of its selectivity towards different compounds - meaning the change of the electrochemical response. The modification agent used in this thesis is 1-octanethiol. Its thiol group offers great potential of strong interaction with the metal surface of the mercury electrode. Voltammetric responses of both compounds were recorded in acidic, neutral and basic solutions (pH=2, pH=7, pH=12) including the responses when the electrode surface was modified. Next objective was the optimization of the modification procedure itself (transferring of the mercury drop from one media to another without damaging or tearing it off from the capillary orifice)....
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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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