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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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Modification of boron doped diamond electrode by poly-L-lysine and its influence on electrochemical behaviour of dopamine and serotonin
Pejzlová, Michaela ; Fischer, Jan (advisor) ; Vyskočil, Vlastimil (referee)
This bachelor's thesis deals with the redox behavior of two neurotransmitters, dopamine and serotonin, at bare anodically activated (O-terminated) and poly-L-lysine-coated boron doped diamond electrode in two media, namely phosphate buffered saline and Neurobasal (medium commonly used for neuron cultivation experiments). Oxidation of dopamine in tested environments has a quasi-reversible character, while serotonin oxidizes irreversibly on boron doped diamond electrode, both O-terminated and poly-L-lysine-treated. Clearly, poly-L-lysine modification of boron doped diamond electrode leads to a decrease in peak currents and a positive shift in oxidation potentials compared to the O-terminated boron doped diamond electrode; interestingly, serotonin is much more sensitive to polymer coating than dopamine, particularly in Neurobasal medium. During successive measurements, a considerable decrease in recorded signals of both neurotransmitters can be observed. Hence, possibilities how to ensure stable current values were investigated: for dopamine, stirring the solution between the individual scans is sufficient method for obtaining repeatable signals (sr = 1.4-11.9 %, n = 5). However, in case of serotonin it is necessary to reactivate the electrode surface anodically in H2SO4 (Eact = +2400 mV) for 5...
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