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Detailed characterization of macrocyclic glycopeptide-based chiral stationary phases in SFC
Folprechtová, Denisa ; Kalíková, Květa (advisor) ; Křížek, Tomáš (referee) ; Kohout, Michal (referee)
The choice of a suitable chiral stationary phase is a key factor for successful enantioseparation in chromatographic methods. Macrocyclic glycopeptides are chiral selectors that, due to their unique structure, allow to interact with the analyte by various types of interactions simultaneously, which contributes to their complex retention and enantiodiscrimination mechanisms. Macrocyclic glycopeptides are widely used chiral stationary phases in liquid chromatography, but they have not been thoroughly tested in sub/supercritical fluid chromatography, which currently rank among important separation techniques in terms of chiral analyses. Therefore, the aim of this thesis is a detailed characterization of the enantiodiscrimination and retention mechanisms of macrocyclic glycopeptide-based chiral stationary phases packed with core-shell particles, namely TeicoShell, VancoShell, and NicoShell columns in sub/supercritical fluid chromatography. First, the effect of the mobile phase composition, especially the type and amount of organic modifiers and additives, on individual chromatographic parameters, i.e., retention, resolution of enantiomers, and peak shapes was studied in detail using selected sets of structurally different biologically active chiral compounds and materials. Based on the obtained...
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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...
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Optimization and validation of analytical method for determination of selected drugs
Geryk, Radim ; Tesařová, Eva (advisor) ; Janečková, Lucie (referee)
The aim of this work was finding suitable conditions for separation of enantiomers of citalopram and citadiol, optimization of chromatographic system and validation of the analytical method for determination of selected enantiomers in drugs. Drugs are often chiral compounds. In many cases, only enantiomer has required pharmacological effects. Advanced chemical technologies associated with the synthesis, separation and analysis of the individual enantiomers caused an increase of the number of new chiral drugs in the form of single pure enantiomers, the chiral switch. Citalopram is one of the widely used antidepressants of selective serotonin reuptake inhibitors (SSRI). Citalopram is used for treatment of depression, panic anxienty or obsessive compulsive disorder of pathological laughing and crying. The pharmacological activity is associated with the S-citalopram, while R-enantiomer is essentially inactive and even counteracts the activity of escitalopram. Citadiol is a chiral syntetic precursor of citalopram. This thesis was focused on monitoring enantioseparation "behaviour" of selected enantiomers. HPLC method with chiral stationary phases based on macrocyclic antibiotics, cyclofructans and cellulose was applied for enantioseparation of the above-mentioned compounds. The optimized chromatographic...
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Separation of chiral liquid crystals
Semeniuk, Lidziya ; Kubíčková, Anna (advisor) ; Kozlík, Petr (referee)
This bachelor thesis focuses on the enantioseparation of selected thermotropic chiral rod- shaped liquid crystals using ultra-high-performance liquid chromatography on a chiral stationary phase working in a reverse mode. The studied chiral liquid crystals are mesogens that form a smectic mesophase. They differ in chemical structure (lengths of alkyl chains, substituents) and have a chiral center derived from two substances - 2-octanol and lactic acid. The current study consists of testing the enantioselective potential of a new UHPLC column Chiralpak IB-U with tris (3,5-dimethyl phenyl carbamate) cellulose as a chiral selector. The optimization of the chromatographic conditions, i.e., temperature and mobile phase flow rate, is performed. Acetonitrile, methanol, ethanol, and deionized water in various ratios are used as mobile phases. The influence of the structure of liquid crystals (namely the presence and the position of fluorine atoms on the benzene nucleus, length of the alkyl chain, nature of the chiral center) on the course of separations, i.e., on retention, enantioselectivity, and resolution, is assessed. The results are compared with published data from similar studies. The influence of the stationary phase on the enantioseparations of interest is discussed. Keywords: ultra-high...
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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...
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Optimization and validation of analytical method for determination of selected drugs
Geryk, Radim ; Tesařová, Eva (advisor) ; Janečková, Lucie (referee)
The aim of this work was finding suitable conditions for separation of enantiomers of citalopram and citadiol, optimization of chromatographic system and validation of the analytical method for determination of selected enantiomers in drugs. Drugs are often chiral compounds. In many cases, only enantiomer has required pharmacological effects. Advanced chemical technologies associated with the synthesis, separation and analysis of the individual enantiomers caused an increase of the number of new chiral drugs in the form of single pure enantiomers, the chiral switch. Citalopram is one of the widely used antidepressants of selective serotonin reuptake inhibitors (SSRI). Citalopram is used for treatment of depression, panic anxienty or obsessive compulsive disorder of pathological laughing and crying. The pharmacological activity is associated with the S-citalopram, while R-enantiomer is essentially inactive and even counteracts the activity of escitalopram. Citadiol is a chiral syntetic precursor of citalopram. This thesis was focused on monitoring enantioseparation "behaviour" of selected enantiomers. HPLC method with chiral stationary phases based on macrocyclic antibiotics, cyclofructans and cellulose was applied for enantioseparation of the above-mentioned compounds. The optimized chromatographic...
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