|
|
Proton conductivity of powder samples
Taraba, Lukáš ; Havlíček, David (advisor) ; Matulková, Irena (referee)
Title: Proton Conductivity of Powder Samples Author: Lukáš Taraba Department: Department of Inorganic Chemistry, Faculty of Science Supervisor: Doc. RNDr. David Havlíček, CSc. Supervisor's e-mail address: david.havlicek@natur.cuni.cz Abstract This bachelor thesis is focused on the possibility of approximate determination of the specific conductivity of powder samples. It is based on X-ray diffraction analysis assuming the possibility of proton transfer by the system of properly arranged short hydrogen bonds in the structure of compounds. The selected substances were freshly prepared for the measurement. A newly prepared and investigated aminoguinidinium(1+) sulphamate was also measured. The specific conductivity of individual polycrystalline materials pressed into pellets or single crystal was calculated from the measured electrical resistance and dimensions of the samples. According to the results, this method of measurementis is fully sufficient for a gross estimate of whether the compound has a specific conductivity higher than that insulants usually have. Keywords proton conductivity - powder sample, hydrogen bond, aminoguanidinium(1+) sulphamate
|
|
|
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
|
|
|
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
|
|
|
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš ; Křížek, Tomáš (advisor) ; Pacáková, Věra (referee) ; Srbek, Jan (referee)
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
|
|
|
Determination of tryptamine and tryptophan in biological material by capillary electrophoresis
Šimonová, Alice ; Křížek, Tomáš (advisor) ; Taraba, Lukáš (referee)
The aim of this bachelor thesis was the development of the method for the determination of tryptamine and tryptophan in biological material by capillary electrophoresis. Total length of silica capillary with inner diameter 75 m was 50.0 cm and effective length was 8.5 cm, injection of the sample was on the short end of the capillary. The composition of background electrolyte, injection method and on-line preconcentration techniques were optimized. Background electrolyte was acetic acid of 1,6 mol/l concentration, sample was injected hydrodynamically with pressure of 5 kPa for 5 s and driving voltage was -30 kV. The analytes were detected at wavelength of 220 nm and the inner standard aniline was detected at wavelength of 200 nm. Time of separation was only 2 minutes, which is the main advantage of this method. The limits of detection were 0.002 mmol/l for tryptamine and 0.001 mmol/l for tryptophan, the limits of quantification were 0.006 mmol/l for tryptamine and 0.005 mmol/l for tryptophan. Repeatability of peak areas and migration times of standards of 0,045 mmol/l concentration related to inner standard showed values of relative standard deviation lower than 5 %. The use of optimized method was tested on Nicotiana tabacum leaves and on cultivating medium of oomycete Pythium oligandrum. Key...
|
|
|
Electrophoretic determination of organic acids in industrial solutions
Taraba, Lukáš ; Křížek, Tomáš (advisor) ; Sobotníková, Jana (referee)
This work deals with the development and optimization of conditions of pretreatment of two industrial surface finishing baths containing chromium(III) ions and oxalic, maleic, acetic or citric acid and their electrophoretic analysis. Some model mixtures containing known amounts of components of industrial solutions have been made for simulation of complex matrices of the real samples. Prior to analysis a sample pre-treatment consisting of different dilution and addition of fluoride, hydroxide or EDTA anions as suitable agent releasing acid out of the stable chromium complex were studied. Determination of organic anions was accomplished by indirect UV detection at 350 nm with a reference at 230 nm. A commercially available background electrolyte, pH 5.7, was used for separation of analytes. The most appropriate pre-treatment to release acids have been achieved by precipitation of chromium(III) hydroxide. The method of standard additions was used for the quantification. The concentrations of oxalate and citrate in the real samples were calculated as 96,50 % (S.D. = 0,71 %) and 97,53 % (S.D. = 0,79 %), respectively, of declared amount. Satisfactory repeatabilities were obtained for both analytes with R.S.D. values (n = 5) for migration times lower than 0,51 %, R.S.D. for peak areas of oxalic acid were...
|
|
|
Proton conductivity of powder samples
Taraba, Lukáš ; Havlíček, David (advisor) ; Matulková, Irena (referee)
Title: Proton Conductivity of Powder Samples Author: Lukáš Taraba Department: Department of Inorganic Chemistry, Faculty of Science Supervisor: Doc. RNDr. David Havlíček, CSc. Supervisor's e-mail address: david.havlicek@natur.cuni.cz Abstract This bachelor thesis is focused on the possibility of approximate determination of the specific conductivity of powder samples. It is based on X-ray diffraction analysis assuming the possibility of proton transfer by the system of properly arranged short hydrogen bonds in the structure of compounds. The selected substances were freshly prepared for the measurement. A newly prepared and investigated aminoguinidinium(1+) sulphamate was also measured. The specific conductivity of individual polycrystalline materials pressed into pellets or single crystal was calculated from the measured electrical resistance and dimensions of the samples. According to the results, this method of measurementis is fully sufficient for a gross estimate of whether the compound has a specific conductivity higher than that insulants usually have. Keywords proton conductivity - powder sample, hydrogen bond, aminoguanidinium(1+) sulphamate
|
guest ::
