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Study of retention and separation of peptides in HPLC
Boudová, Hana ; Kalíková, Květa (advisor) ; Kubíčková, Anna (referee)
This diploma thesis deals with the study of retention and separation of structurally different peptides and digest products of cytochrome c using reverse phase and mixed modes of liquid chromatography. As the model peptides, five unmodified dipeptides, nine dipeptides containing a protective benzoyl group on the N-terminal amino acid and eight therapeutic peptides containing five to ten amino acids were selected. The chromatographic behaviour of the model peptides was tested on three different columns: XBridge C18, XSelect CSH C18 and Atlantis Premier BEH C18 AX under different conditions. The influence of the pH of the aqueous part of the mobile phase, i.e. 2,1; 3,0; 4,7 and 6,8, and the amount of acetonitrile in the mobile phase on retention and separation of model peptides was tested. The effect of the concentration of ammonium acetate buffer, pH = 6,8 in the mobile phase on the retention and peak symmetry in the concentration range of 10-50 mmol L-1 was assessed. The chromatographic conditions for the baseline separation of 20 different model peptides were optimized. The conditions were as follows: XSelect CSH C18 column, mobile phase composed of acetonitrile/10mM ammonium acetate, pH = 6,8 (v/v) under gradient elution. The suitable chromatographic conditions for the analysis and identification...
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Characterization and comparison of new reversed-phase HPLC columns
Putzová, Klára ; Kalíková, Květa (advisor) ; Kozlík, Petr (referee)
The aim of the bachelor thesis was to evaluate and compare interaction/separation properties of three chromatographic columns, namely XBridge C18, XSelect CSH C18 XSelect HSS C18, designed for reversed-phase high performance liquid chromatography. All the columns contain the same ligand, i.e. octadecyl but they differ in the stationary phase support. The columns were compared in terms of silanol activity, hydrophobicity, shape selectivity and efficiency. For this purpose, the simple chromatographic tests designed by Walters, Engelhardt and Galushko were used. Furthermore, the separation of five selected pesticides, namely acetochlor, fomesafen, isoproturon, metazachlor triflumuron, were optimized on tested columns in simple mobile phases composed of acetonitrile or methanol as organic modifiers and water. All the tested columns showed low silanol activity and medium to high hydrophobicity acording to the chromatographic tests used. The low silanol activity corelates with endcapping procedure used for all the columns. All pesticides were more retained in methanolic mobile phase due to the lower elution strength of methanol compared to acetonitrile in reversed-phase high performance liquid chromatography. The analysis time of separation varied for each column under the same chromatographic conditions. The...
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Cold adaptation in stationary phase in Bacillus subtilis
Beranová, Anna ; Konopásek, Ivo (advisor) ; Svobodová, Jaroslava (referee)
Cold adaptation in stationary phase in Bacillus subtilis One of the most important abiotic factor which influences life of bacterial cells is the ambient temperature. A decrease of this temperature is usually accompanied usually with the loss of the fluidity of bacterial cytoplasmatic membrane. While the mechanisms of the responses to the cold shock during the exponential phase of growth are well known for Bacillus subtilis, the responses of stationary phase cells had not been studied yet (despite the stationary phase is the most common state of microorganism in the nature). There are two independent mechanisms which restores much needed fluidity in Bacillus subtilis - short-term adaptation and long-term adaptation. Short-term adaptation is based on the function of fatty acid desaturase coded by des gene. Long-term adaptation relies on the change in ratio of iso- and anteiso- branched fatty acids. In this work we examinated membrane adaptation during stationary phase under two different conditions, namely under cultivation at stable low temperature and after cold shock. The highest activity of Pdes was observed for cultivation at 25 řC and for the cold shock applied from cultivation in 37 řC to 25 řC. Anisotropy measurements and fatty acids analysis were also performed. Results indicated, that the...
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Chromatograhic characterization of chiral and achiral separation systems
Kučerová, Gabriela ; Tesařová, Eva (advisor) ; Čabala, Radomír (referee) ; Ševčík, Juraj (referee)
Dissertation thesis is a 5-publications' collection concerning characterization and application potential of cyclodextrins, polysaccharides and macrocyclic antibiotics based chiral stationary phases. The effects of stationary phase and mobile phase are studied. This approach ensures the complex insight into separation systems studied. Systems with different nature of chiral selector were studied by HPLC. Namely, macrocyclic antibiotics and derivatized polysaccharides were used for experiments. Former ones provided better results for enantioseparation of non-coded amino acids than latter ones. Dynamic coating procedure was used for preparation of a new chiral stationary phase. Characterization of new cationic cyclodextrin based chiral stationary phase was performed. Linear free energy relationship method was used for characterization of two different separation systems, i.e. newly prepared stationary phase and commercially available stationary phase. Based on results obtained, newly prepared stationary phase showed better results for separation of different achiral groups of analysts. New stationary phase prepared by dynamic coating was compared with chromatographic system, in which the chiral selector was used as a mobile phase additive. The chiral selector used for the two different approaches was...
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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....
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Characterization and comparison of new reversed-phase HPLC columns
Putzová, Klára ; Kalíková, Květa (advisor) ; Kozlík, Petr (referee)
The aim of the bachelor thesis was to evaluate and compare interaction/separation properties of three chromatographic columns, namely XBridge C18, XSelect CSH C18 XSelect HSS C18, designed for reversed-phase high performance liquid chromatography. All the columns contain the same ligand, i.e. octadecyl but they differ in the stationary phase support. The columns were compared in terms of silanol activity, hydrophobicity, shape selectivity and efficiency. For this purpose, the simple chromatographic tests designed by Walters, Engelhardt and Galushko were used. Furthermore, the separation of five selected pesticides, namely acetochlor, fomesafen, isoproturon, metazachlor triflumuron, were optimized on tested columns in simple mobile phases composed of acetonitrile or methanol as organic modifiers and water. All the tested columns showed low silanol activity and medium to high hydrophobicity acording to the chromatographic tests used. The low silanol activity corelates with endcapping procedure used for all the columns. All pesticides were more retained in methanolic mobile phase due to the lower elution strength of methanol compared to acetonitrile in reversed-phase high performance liquid chromatography. The analysis time of separation varied for each column under the same chromatographic conditions. The...
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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....
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Utilization of polynailine in separation methods
Riečan, Martin ; Sobotníková, Jana (advisor) ; Křížek, Tomáš (referee)
Submitted master thesis is by its character focused on development of polyaniline which would possess attributes typical for monolithic stationary phase. Developed polyaniline aims to be used in capillary liquid chromatography. Accompanying target of submitted master thesis is to provide solutions for variety of complications which follow the preparation of polyaniline in its desired form such as consistency in a form of solutions, gels and pastes, extremely fast polymerization reaction, limited solubility of cross-linking agents, solubility of monolithic polyaniline in polar mobile phases and insufficient bond of polyaniline to the inner wall of fused silica capillary tubing. Solutions for this complications are selection of ideal oxidation agent (ammonium persulfate), cross-linking agent (tris(4-aminophenyl)amine) and porogenic agent (methanol). Also, setting ideal ratio between oxidation agent, cross-linking agent and porogenic agent, heat treatment, choice of suitable mobile phase (tetrahydrofuran), adjustment of capillary wall using silanization agent (3-[3-(trimethoxysilyl)propyl]-aniline) and construction of equipment needed for quick filling of capillaries. Described development concluded in the preparation of solid polyaniline monolith which had a steady bond to the inner wall of fused...
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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....
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Chromatograhic characterization of chiral and achiral separation systems
Kučerová, Gabriela ; Tesařová, Eva (advisor) ; Čabala, Radomír (referee) ; Ševčík, Juraj (referee)
Dissertation thesis is a 5-publications' collection concerning characterization and application potential of cyclodextrins, polysaccharides and macrocyclic antibiotics based chiral stationary phases. The effects of stationary phase and mobile phase are studied. This approach ensures the complex insight into separation systems studied. Systems with different nature of chiral selector were studied by HPLC. Namely, macrocyclic antibiotics and derivatized polysaccharides were used for experiments. Former ones provided better results for enantioseparation of non-coded amino acids than latter ones. Dynamic coating procedure was used for preparation of a new chiral stationary phase. Characterization of new cationic cyclodextrin based chiral stationary phase was performed. Linear free energy relationship method was used for characterization of two different separation systems, i.e. newly prepared stationary phase and commercially available stationary phase. Based on results obtained, newly prepared stationary phase showed better results for separation of different achiral groups of analysts. New stationary phase prepared by dynamic coating was compared with chromatographic system, in which the chiral selector was used as a mobile phase additive. The chiral selector used for the two different approaches was...
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