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Device for measurement of electrochemical cells characteristics by the cyclic voltammetry
Kučera, Vojtěch ; Bilko, Radek (referee) ; Lábus, Radek (advisor)
The thesis deals with observation of cells parameters. One of the potential solutions for observing the characteristics of cells are utilization the electrochemical analyse called voltametry. Its fundamental consists of loading variable voltage in between two electrodes dipped in electrolytic solution and monitoring flowing current. The point of the thesis is to build up the measuring workplace, which can provide this measurement. We suggest utilization of modern laboratory technique and connection the measuring instruments with PC. The first part of the thesis deals with theoretical knowledge of used functions and describes theirs mathematics definitions. The second part deals with proceeding of workplace realization, instrument connection with PC and development application in computer’s language. Result is measuring workplace, which can provide observing cells according to entered parameters.
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Spray-coated working electrodes of electrochemical sensors
Lechner, Filip ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This thesis is about the selection of the better type of thick film working electrode for the detection of substances in aqueous solutions, modified by spray coated carbon nanotubes. The theoretical part of this thesis describes the technology of thick film, properties and production of carbon nanotubes, introduction to electrochemistry and electroanalytical methods for the detection of substances in aqueous solutions. The practical part is aimed to realization of the working electrodes by thick film technology and their modification by spray-coated layer consist of carbon nanotubes. Electrodes are characterized using voltammetric methods, electrochemical impedance spectroscopy and electron microscopy. In conclusions is selected the most suitable type of working electrodes for reproducible electrochemical analysis.
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Electrolytes characterization based on mixtures of ionic liquids and aprotic solvents
Šašek, Martin ; Libich, Jiří (referee) ; Máca, Josef (advisor)
The thesis deals with liquid aprotic electrolytes based on mixtures of ionic liquid and solvent. EmimBF4, namely 1-ethyl-3-ethylimidazolium tetrafluoroborate, was used as the starting ionic liquid. A mixture of propylene carbonate, ethylene carbonate and dimethyl carbonate was used as solvents. Electrolytes were enriched with two electrolyte salts LiBF4 and NaBF4 from the resulting mixtures selected the most suitable electrolytes for Li-ion and Na-ion accumulators. Electrolytes were selected taking into account the required properties: the width of the potential window, the measured electrical conductivity and, last but not least, the safety.
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Zinc in food suplements
Sauchanka, Katsiaryna ; Suková, Petra (referee) ; Řezáčová, Veronika (advisor)
The aim of this bachelor thesis was to determine zinc in the dietary supplements by the voltammetric method. The general properties of zinc, its occurrence, toxicity and influence on human health are described in the first part. Next the methods, including a detailed description of the voltammetric analysis, are summarized. The experimental part is focused on the process of optimization of the conditions for zinc voltammetric analysis and the application of the optimised method on real samples.
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The electrochemical sensors with 3-D structure of electrodes
Štekovič, Michal ; Hrdý, Radim (referee) ; Adámek, Martin (advisor)
Miniature electrochemical sensors can be produced by thick-film technology. The optimal properties of thick-film electrode system, the production technology optimization of thick-film sensors and the adjustment of optimal technological properties are main problems of sensor design. An area of working electrode and an electrode topology design is the important parts in design of electrode system optimization. The rules for optimization of electrode systems in classical electrochemistry exist. The design of standard thick-film electrode construction is limited (2-D construction, substrate dimensions, resolution, paste parameters …). Therefore rules for classical electrode systems cannot be used fully in this case and larger electrode area can be making by 3D structure only. One of resolutions is unconventional method. The increase of working electrode surface by unconventional method – ball and wire bonding is discussed in this work.
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Optical determination of the state of charge of vanadium flow battery cells
Šacl, Vojtěch ; Chladil, Ladislav (referee) ; Novák, Vítězslav (advisor)
The investigated subject for this diploma thesis is getting know properties of the vanadium redox battery (VRB), especially electrolyte. Specialization is applied to the state of charge of this cell and its measurements using the optical methods. Upon different state of charge is changed oxidation number of vanadium and resultant color of the electrolyte. Using spectrofotometry method that characteristic property is undergone measurement. The basic thing was learning to handle a measurement system. The first practical measurement was executed on example foils. Upon measurement of vanadium cell there was obtained the values of absorbation, which they were used for determination of state of charge.
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Development of electroanalytical methods for detection of cholesterol, 7-dehydrocholesterol and cholecalciferol
Benešová, Lenka
Steroidival substances are an integral part of the human organism, such as bile acids, steroid hormones, vitamins. The most important sterol in whole organism is cholesterol, which is cornerstone of the all cell membranes. It is involved in important processes in the body, but its storage in blood vessels in the formo f low-density lipoprotein (LDL) is crucial of reason serious health diseases as atherosclerosis, myocardial infarction and others. 7-dehydrocholesterol is a precursor of cholesterol and another sterol compound studied by me, cholekalciferol, also known as a vitamin D3. Deficiency of 7-dehydrocholesterol reductase is the main indicatior of the possible genesis of Smith-Lemli-Opitz syndrome. One of the goals of this thesis was developed a suitable electrochemical method to facilitate the diagnosis of this syndrome from plasma and amniotic fluid in the prenatal and postnatal phases of pregnancy. Within the framework of this thesis were developer electrochemical methods in a batch and flow arrangement for detection of the above-mentioned sterols, namely cholesterol, 7-dehydrocholesterol and cholekalciferol. It was wokered in the medium contain perchloric acid or its salt sodium perchlorate in acetonitrile as supporting electrolyte. It was worked in the wide range of working disc...
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Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
Propyl gallate (PG) is a significant synthetic antioxidant and preservative. Its determination has been studied at carbon paste electrode (CPE) using differential pulse voltammetry (DPV) and high performance liquid chromatography with electrochemical detection (HPLC-ED) and with UV spectrometric detection (HPLC-UV). Concentration dependences were measured in the media of Britton-Robinson buffer (pH 5) and methanol (20 %, v/v) by DPV and the limit of detection 0,6110-7 moldm-3 was obtained. Using HPLC with a mobile phase consisting of 0,01 moldm-3 phosphate buffer (pH 4) and methanol (50 %, v/v) with potential of working electrode E = +0,8 V and detection wavelength λ = 280 nm, concentration dependences were measured. Limit of detection was determined to 0,39 moldm-3 for HPLC-ED and 4,95 moldm-3 for HPLC-UV. After verification of the extraction procedure PG was determined in vegetable oil. The resulting value of 3,2 mgkg-1 corresponds with permited limits.
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