|
|
Determination of ethanol in petrol using impedance detector
Kadlecová, Tereza ; Opekar, František (advisor) ; Štulík, Karel (referee)
This work deals with the determination of ethanol in petrol using contactless impedance detector. Planar and tubular detection cells of various geometric parameters are tested. The cells are connected as a frequency determining capacitor in an integrated multivibrator circuit. Analyzed gasoline, whose dielectric constant depends on the ethanol content, forms the dieletric of the capacity cells. Therefore, for various contents of ethanol, the capacity of the detection cells varies and the multivibrator generates different frequency. Based on the calibration, the content of ethanol can be determined from the frequency measured. The results obtained are compared with those obtained by gas chromatography with mass spectrometric detection.
|
|
|
Applications of ionic liquids in electrolytes for amperometric gas sensors and Li-ion batteries.
Nádherná, Martina ; Opekar, František (advisor) ; Samec, Zdeněk (referee) ; Zima, Jiří (referee)
Mgr. Martina Nádherná PhD. Thesis Applications of ionic liquids in electrolytes for amperometric gas sensors and Li-ion batteries SUMMARY The dissertation presents the results of preparation and characterisation of new aprotic electrolytes based on ionic liquids for the solid-state electrochemical gas sensors and for the electrochemical energy storage devices - secondary lithium-ion batteries. In the part dealing with the solid-state amperometric sensor for NO2 research was aimed at development of new solid electrolyte. This electrolyte is developed as a system of ionic liquid embedded in the structure of a polymer, when the ionic liquid joints the properties of a solvent and a dissolved salt. The electrolyte therefore does not contain any volatile component and is long-term chemically and electrochemically stable. Several series of electrolytes were prepared with different polymers or macromonomers and imidazolium-based ionic liquids. The composition, especially the polymer-IL ratio was optimized. The electrolytes were successfully tested in a solid-state NO2 sensor with a gold minigrid serving as the indicating electrode. The research included the determination of basic electrochemical parameters and study of the sensor behaviour under different conditions. The influence of atmosphere humidity,...
|
|
|
Electrophoretic separations of saccharides in short capillary.
Vochyánová, Blanka ; Opekar, František (advisor) ; Jelínek, Ivan (referee)
A new laboratory system has been developed for rapid electrophoretic separations and determinations of inorganic and organic ions. The instrument employs short fused silica capillary in combination with contactless conductivity detection. The basic functions of the apparatus have been tested using mixture of inorganic ions. It has further been applied to separations of neutral mono- and disaccharides. The model mixture contains five saccharides (sucrose, lactose, glucose, fructose and ribose). The technique developed has been used to determine sucrose, glucose and fructose in high-energy drinks.
|
|
|
The Titrimetric determination with thermometric detection.
Nohavová, Ivana ; Opekar, František (advisor) ; Coufal, Pavel (referee)
Thermometric detection is one of the less usual methods for the objective titration end- point detection. The temperature change at the reaction between an analyte and a titration reagent is monitored by a thermistor. Break-response to the volume of an added titrant indicates reaching the end point of the titration. Subject of this work is to develop a method for the titrimetric determination of acids and bases with this detection method.
|
|
| |
|
|
Impedimetric contactless detection of compounds in gas phase
Pavlíček, Václav ; Opekar, František (advisor) ; Štulík, Karel (referee)
Simple and sensitive detector based on contactless impedance detection has been tested. The detection cell consists of two insulated wire electrodes placed in a PTFE tube through which the test vapour phase flows. It has been found that the detector is sufficiently sensitive and reliable for determinations of common concentrations of water vapour in the air. Qualitative tests indicate that the vapour of organic solvents can also be monitored. This is the first application of contactless impedance detection of compounds in the gaseous phase based on a new instrumental approach to impedance detection. Keywords: Impedance detection, Contactless impedance detector, Vapour phase, Relative humidity, Organic solvent vapour
|
|
|
Electrophoresis in short capillaries
Podhorná, Petra ; Opekar, František (advisor) ; Samcová, Eva (referee)
The laboratory-made apparatus for electrophoretic separations in short capillaries has been tested. The basic functions of the apparatus (separation efficiency, resolution, migration time) have been tested using mixture of K+ and Na+ ions. The model mixture of basic amino-acids (arginine, lysine, histidine and its derivatives, 3-methylhistidine and 1-methylhistidine) has also been separated and detected using contactless conductometric detector. Histidine in real sample of urine has also been determined. Keywords: capillary electrophoresis, short capillary, alkaline aminoacids
|
|
| |
|
| |
|
|
Volumetric determination of weak and strong acid in the mixture.
Norková, Renáta ; Opekar, František (advisor) ; Jelínek, Ivan (referee)
The project is aimed to the study of the titration curves of the weak and strong acid mixtures. Purpose of the project is to compare titration curves computed on the basis of simple model, when neglecting influence of the solution's ionic strength , with experimental titration curve obtained through measuring under standard laboratory conditions. This comparison is carried out for one strong acid in the mixture with various weak acids, that differ in value of dissociation constant. How titration curves are influenced by the ratio of concentration of strong and weak acids is observed further.
|
guest ::
