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Electrochemical detection of n-propanol on Au and Pt electrodes modified with polyaniline-based composites
Pejzlová, Michaela ; Fischer, Jan (advisor) ; Vyskočil, Vlastimil (referee)
The electrochemical oxidation of aliphatic alcohols is problematic on conventional electrode materials and to develop methods for their detection, the catalytic properties of electrode surfaces need to be exploited. This thesis is concerned with the study of the electrochemical deposition of polyaniline (PANI) in acidic media on three different electrodes, platinum, gold and glassy carbon electrode. The properties of the PANI modified electrodes were tested in comparison to the unmodified electrodes. The electrooxidation of aliphatic alcohols n-propanol and 2-propanol in alkaline medium was studied by cyclic voltammetry. Subsequently, the effect of electrodeposited noble metals (palladium and gold) on the surfaces of unmodified and PANI modified electrodes on the electrooxidation of propanol was investigated by using the same procedures. From the linear part of the concentration dependence of n-propanol on the chosen electrodes, the limit of detection was determined. The lowest value was calculated for the platinum electrode with electrodeposited gold (LOD = 0.2 mmol l−1 ). PANI modified electrodes showed wider linear dynamic range than electrodes without this modification. Keywords: cyclic voltammetry, electrooxidation, glassy carbon electrode, gold electrode, metal electrodeposition, n-propanol,...
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Comparison of the gold microelectrode and conventional electrode for the saccharide determination using pulsed amperometry
Smítková, Karolína ; Dejmková, Hana (advisor) ; Schwarzová, Karolina (referee)
This bachelor's thesis deals with combination of pulsed amperometric detection (PAD) with flow injection analysis (FIA) in order to use them to detect glucose and consequently carbohydrates in solution. Pulsed amperometry is efficient detection method for many of organic compounds in which, as the name suggests, a sequence of three or four potential pulses is applied at the working electrode. If the pulse parameters are suitable, then it is possible to eliminate the unwanted passivation of the working electrode due to the adsorption of oxidation products and intermediate products of aliphatic compounds, which would lead to a reducion of its active surface. The aim od this work is to show the effect of the change of the value of the applied potential pulses on the peak heights corresponding to the oxidation of the glucose in solution and to evaluate their repeatability. As a working electrode, it compares a gold electrode of conventional size and a gold microelectrode. The determination was performed in a borate buffer with pH = 10. First of all, cyclic voltammograms of solution with concentration of glucose 1·10-2 mol dm-3 were measured to obtain the initial values of the applied pulses. Subsequently, the dependence of the peak heights on their injection order for different values of individual...
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Determination of creatinine using pulsed amperometry
Giampaglia, Dominika ; Dejmková, Hana (advisor) ; Schwarzová, Karolina (referee)
This diploma thesis deals with the determination of creatinine using a combination of flow injection analysis (FIA) or high-performance liquid chromatography (HPLC) with pulse amperometry, an electrochemical technique based on the application of potential pulses on a gold working electrode. The determination was performed in a basic environment of borate buffer with creatinine concentration of 1∙10-4 mol∙l-1 . The lenght of the cleaning and activation pulse was optimized as well as the pH of the running buffer. A cleaning pulse of +1.8 V was first applied to the electrode for 100 ms, then an activation potential of -0.5 V was applied for 150 ms and then a measuring potential of +0.2 V for 300 ms. The optimal pH was selected as pH=9,4. Methanol and acetonitrile were added to the borate buffer to test whether creatinine could be determined in presence of these organic solvents and whether flow injection analysis could be transformed into HPLC. Methanol in the system caused peak deformation, acetonitrile did not cause the peak deformation in the system, at higher contents the baseline was destabilized. Furthermore, the calibration dependence in the range of concentrations from 2.5∙10-4 mol∙l-1 to 5∙10-6 mol ∙ l-1 was measured using PAD in combination with FIA. At higher concentrations, peaks splitted....
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Preparation and Characterization of Silver Amalgam Particles on Gold Electrode Surface
Havranová-Vidláková, Pavlína ; Šebest, Peter ; Ligmajer, Filip ; Fojta, Miroslav ; Daňhel, Aleš
This work is focused on the preparation of silver amalgam particles by its direct electrodeposition on gold surfaces using double pulse chronoamperometry from solution containing soluble Ag+ and Hg2+ ionts. During the electrodepositions of silver amalgam particles, different: i) parameters of chronoamperometry, ii) Ag/Hg ratio in solution and iii) gold electrodes were studied. All the prepared amalgam particles were characterized by scanning electron microscope with energy dispersive X-ray spectroscopy and electrochemical methods. Voltammetric application of the gold electrodes decorated by sliver amalgam particles was confirmed by analysis of model organic nitrocompound using cyclic voltammetry.
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Study of Electrochemical Behaviour of Gold Nanostructured Surfaces
Kynclová, Hana
Recently, nanostructured surfaces have been extensively studied due to their possibility to use them in construction of electrochemical sensors and biosensors. We have prepared tungsten working electrode modified with gold nanocolumns via galvanic deposition of gold ions through anodic alumina nanoporous template. This nanostructured surface was subsequently electrochemically characterized by cyclic voltammetry using K3[Fe(CN)6]/K4[Fe(CN)6] probe and compared with the results measured on a flat gold electrode. The electroactive areas for both types of electrodes were evaluated and compared. It was found that the nanostructured area affected the response on lower scan rates (up to 25 mV.s-1) and increased the response at higher scan rates (higher than 50 mV.s-1) which is probably related to penetration of electrolyte solution among nanocolumns. Nevertheless, this fact can help in speed of analyses of huge amount of samples.
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Preparation of modified gold electrodes for quartz microbalance
Králová, Miroslava ; Jelínek, Ivan (advisor) ; Čabala, Radomír (referee)
This diploma work is devoted to the preparation and analytical testing of modified gold electrodes in QCM. The sensitivity and selectivity response towards selected aromatic analytes in aqueous phase was monitored. Studied analytes were 1-methylnaphthalene, 2-methylnaphthalene, naphthalene, o-xylene and toluene. These compounds are frequently used in chemistry industry and other industrial branches and, are known to be harmful to human organism and environment. Using QCM method it is possible to detect them rapidly and relatively easily.
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A study of calixarene self-assembled monolayers on gold metal surfaces
Šustrová, Barbora ; Mareček, Vladimír ; Štulík, Karel
Substituted calix[4]arene molecules were self-assembled on the gold disk electrode surface and the structure of the monolayer formed and the electrochemical behavior of the modified electrode were studied. The formation of the calixarene self-assembled monolayer (SAM) conformed to a Langmuir-type adsorption isotherm, The atomic force microscopy measurement results indicated that the calixarene molecules form a stable monolayer on the Au(111) surface and confirmed the cyclic voltammetry results concerning the SAM structure dependence on the solvent used. Impedance measurements demonstrate that the capacity of the modified electrode varies in the presence of ions, depending on their size and shape.
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