|
|
Study of retention and separation of pesticides in different modes of liquid chromatography
Dérerová, Tímea ; Kalíková, Květa (advisor) ; Riesová, Martina (referee)
4 Abstract This bachelor thesis is focused on a separation of six pesticides in reversed-phase and mixed-mode high performance liquid chromatography using Atlantis dC18, XSelect CSH C18, XSelect CSH Fluro-Phenyl and Atlantis Premier BEH C18 AX columns. The same manufacturing parameters - column and carrier particle dimensions opened up the possibility of their direct comparison in terms of retentivity and selectivity. The stationary phases were categorized using Walters test, in terms of hydrofobicity, silanol activity and efficiency. The analytes of interest were pesticides with a different mechanism of action in the environment. Two of them contained an acidic functional group that caused their elution at system void volume if pure water was used as aqueous part of mobile phase. For suppression of dissociation of acidic pesticides, the buffers, i.e., 10mM ammonium acetate, pH 4.7 and 10mM ammonium formate, pH 3.0 were used instead of pure water. Tested columns exhibited different retention and selectivity of analytes. For separation conditions optimization, an experimental approach, including changes in mobile phase composition and pH, and separation temperature, was used. Retention time, resolution and peak shape were all dependent on these chromatographic parameters. The retention of tested pesticides...
|
|
|
Monitoring of water quality in protected landscape area streams - Křivoklátsko
Kesnerová, Lucie ; Benešová, Libuše (advisor) ; Riesová, Martina (referee)
This thesis deals with monitoring of surface water quality in CHKO Křivoklátsko. The main purpose of monitoring is to obtain information about a state of flow and development during the previous period and to determine the pollution stage according to relevant standards. The theoretical part describes the basic information about the locality where they come from water samples and basic characteristics of sets of parameters. This section also includes theoretical assesment of sediment. The experimental part shows the practical determinates of each parameter, with the calculation of the quantities present and physical indicators. This section is followed by evaluation of measurement results, which are arranged in tables, including readings of all required parameters. The paper concludes an assessment of the monitoring of quality and compare the current state compared with the previous reporting period at each sampling point. Key words: chemical composition of water, water quality, sediments
|
|
|
Determination of limiting electrophoretic mobilities of charged cyclodextrins
Boublík, Milan ; Riesová, Martina (advisor) ; Křížek, Tomáš (referee)
In the frame of this work, dependences of electrophoretic mobilities of four defined multiple charged cyclodextrins on ionic strength of background electrolyte were measured using capillary zone electrophoresis. Dependencies of mobility on ionic strength do not follow Onsager law in the case of large and multiple charged species. Therefore, empirical fitting function was used to determine limiting mobilities of studied cyclodextrins. Obtained values of limiting mobilities as well as the resulting regression function are essential for correct determination of complexation constants of corresponding cyclodextrins with various analytes.
|
|
|
Chiral HPLC separation of newly synthesized amino acids
Kučerová, Gabriela ; Kalíková, Květa (advisor) ; Riesová, Martina (referee)
The aim of this work was to develop and to optimize HPLC method for enantioseparation of newly synthesized derivatives of amino acids. The set of these analytes contained four N- blocked derivatives of D,L-Phenylalanine, three N-unblocked derivatives of D,L- Phenylalanine, , one methylated derivative of D,L-Tyrosine and D,L-Tyrosine. Two separation modes i.e. reversed phase and polar-organic modes and two columns i.e. Chirobiotic® T and Chirobiotic® T2 were used. Chiral stationary phases of these columns were composed of macrocyclic antibiotic teicoplanin coated on silica gel support. As mobile phases in revesed phase mode, methanol and acetate buffer were used with Chirobiotic® T column. The most suitable concentration were 20 mM and the most suitable pH value were 4.00. Under the above mentioned conditions eight analytes of ten were separated and the optimal conditions were found. Polar-organic mode and Chirobiotic® T column were suitable only for enantioseparation of three N-blocked derivatives of D,L- Phenylalanine. Mobile phases were composed of methanol with small additions of triethylamine and acetic acid. Chirobiotic® T2 column in reversed phase mode was not suitable for tested set of analytes. Only partial separation of D,L-Tyrosine derivative and one N-unblocked D,L-Phenylalanine...
|
|
| |
|
|
Oscillating electrolytes in electrophoresis
Riesová, Martina
Oscillating electrophoretic systems are systems exhibiting oscillations in concentration profiles of all ions when electric current is passing through them. These systems were predicted from linear model of electromigration and the oscillations are a direct consequence of complex system eigenmobilities. We searched for ternary oscillating systems composed of two acids and one base. A tool we used was program PeakMaster, which was modified to enable easier and faster finding of systems with complex eigenmobilities and optimization of their composition. We found eight ternary systems with complex eigenmobility and inspected them experimentally. Five of them proved oscillating behavior. We also found one quaternary oscillating system. To compare theory and experiment we calculated in PeakMaster a theoretical position of the system zones with complex eigenmobilities. In experiments we recognized the system zones like a small gap in the pattern of oscillation. Position of this gap was in very good agreement with theoretical prediction by PeakMaster. We confirmed that the complete oscillating pattern travels in the capillary with velocity determined by real part of complex eigenmobility. Also we tested a robustness of oscillation in some systems and compared simulated the amplitude of oscillations with...
|
|
| |
|
| |
|
|
Electrophoretic systems containing charged cyclodextrins
Boublík, Milan ; Riesová, Martina (advisor) ; Křížek, Tomáš (referee)
Cyclodextrins are frequently used in capillary electromigration separation techniques as a complexing agent. Their presence in background electrolyte can enhance selectivity, mobilize neutral analytes or cause separation of chiral analytes. However, cyclodextrins can complex also with buffer constituents. This type of complexation can lead to significant changes of background electrolyte properties and, consequently, may result in distortion of electrophoretic results. In case of neutral additives, complexation can be easily detected by means of pH changes measurement. Situation in background electrolytes containing charged additives is more complicated due to the change of ionic strength. This work is focused on the revealing of unwanted complexations in systems containing charged cyclodextrins and on proposing safe, i.e. noninteracting, buffers for electrophoretic measurements in presence of charged cyclodextrins. Keywords capillary electrophoresis, affinity capillary electrophoresis, cyclodextrin, background electrolyte, complexation
|
|
|
Cellulose-based chiral stationary phases for reversed phase HPLC
Plecitá, Denisa ; Kalíková, Květa (advisor) ; Riesová, Martina (referee)
This diploma thesis is focused on the comparison of enantioselective potential of chiral stationary phases based on derivatized cellulose by high performance liquid chromatography (HPLC). Polysaccharide - based chiral stationary phases are suitable choice for enantioseparation of various chiral compounds. In this work Chiralpak IB column containing cellulose tris(3,5-dimethylphenylcarbamate) selector immobilized onto silica gel and Chiralpak IC column containing cellulose tris(3,5- dichlorophenylcarbamate) selector immobilized onto silica gel were used. Their ability of enantioseparation was tested on 28 structurally different chiral analytes. Reversed- phase separation mode was used for enantioseparation. Mobile phases were composed of organic modifiers acetonitrile or methanol and the aqueous part was selected according to the nature of analytes. Acidic analytes were separated in mobile phases containing aqueous solution of formic acid (pH 2.1). Analytes of bifunctional nature were separated in the presence of aqueous solution of formic acid (pH 2.1), 10 mM ammonium acetate buffer (pH 8.8) or 100 mM solution of KPF6. Mobile phases containing 10 mM ammonium acetate buffer (pH 8.8) or 100 mM solution of KPF6 were used for enantioseparation of alkaline chiral analytes. Twelve chiral analytes were...
|
guest ::
