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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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Enantioseparations of liquid crystalline materials
Vaňkátová, Petra ; Kubíčková, Anna (advisor) ; Čabala, Radomír (referee) ; Kohout, Michal (referee)
(EN) Liquid crystalline materials are an important domain of the material science. Chiral liquid crystals (CLCs) are researched for their unique chirality-derived properties. The development of new CLCs focuses both on appropriate molecular design to fit their intended purpose and also on ways of using widely available and less expensive sources of chirality to enable cost- effective production for a potential large-scale production. Methods capable of enantioseparation are needed mainly for chiral purity control of newly synthesized CLCs and for their potential use in scaling up for preparative purpose. Nowadays, enantioselective chromatography has evolved to be the method of choice for enantioseparations. This thesis aims to establish new approaches to chromatographic enantioseparations of CLCs by developing fast and robust enantioselective methods using two different ultra-high performance chromatographic techniques - sub/supercritical fluid chromatography (UHPSFC) and liquid chromatography (UHPLC). UHPSFC is introduced and successfully employed for the first time for this purpose. For some CLCs, high values of enantioselectivity and enantioresolution were achieved, opening the possibility of scaling up to semipreparative use. In UHPLC, two modes (reversed-phase and polar organic solvent mode)...
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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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Chiral separation of biologically active compounds by chromatography
Landl, David ; Kalíková, Květa (advisor) ; Kubíčková, Anna (referee)
- 4 - Abstract in English This diploma thesis is focused on the evaluation and comparison of the enantioselective potential of two columns CHIRAL ART Amylose-SA and CDShell-RSP using a set of 29 chiral drugs in high performance liquid chromatography. The separations of enantiomers were performed in three modes: reversed-phase, normal-phase, and polar- organic mode. The CHIRAL ART Amylose-SA column was tested in normal-phase mode, the CDShell-RSP column in reversed-phase and polar-organic modes. The CHIRAL ART Amylose-SA column contains amylose tris(3,5- dimethylphenylcarbamate) immobilized on 3 µm porous silica gel particles. The CDShell-RSP column contains a chiral selector hydroxypropyl-β-cyclodextrin, which is covalently bonded on 2.7 µm superficially porous particles. In the normal-phase mode, mobile phases composed of hexane and propane-2-ol were used. Furthermore, the effect of various additives (triethylamine, diethylamine, trifluoroacetic acid, and the mixture of diethylamine and trifluoroacetic acid) in the mobile phase on the enantioseparation of chiral drugs was tested. The most universal additive was a mixture of diethylamine and trifluoroacetic acid. A total of 22 chiral drugs were enantioseparated on the CHIRAL ART Amylose-SA column, 10 of them were baseline separated. Mobile phases for...
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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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Separation of chiral compounds
Šrolerová, Tereza ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
This bachelor thesis deals with the chiral separation of newly synthesized orthoconic antiferroelectric liquid crystals using ultra-high performance liquid chromatography. These studied compounds differ in the alkyloxy-spacer length, in the presence and/or position of the fluorine atom on the phenyl ring and in the chiral center. The separation took place in a reverse separation mode using a chiral stationary phase based on derivatized amylose. First, the effect of mobile phase flow rate and column temperature on separation efficiency was exanimated. The effect of the composition of the mobile phase on the enantioseparation were studied at the optimum temperature and flow rate. The mobile phase was based on acetonitril, while deionized water was added gradually using isocratic elution. Furthermore, the effect of chromatographic conditions and the structure of the studied analytes on resolution and enantioselectivity was investigated, concretely the presence and position of fluorine atom on pfenyl ring, the length of alkyloxy-spacer and the effect of divergent chiral center. Under optimized chromatography conditions we succeeded to separate all examined substances on the base line. Key words: ultra-high performance chromatography, liquid crystals, enantioseparation, chiral stationary phase, reverse mode
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Chiral separation of biologically active compounds by chromatography
Landl, David ; Kalíková, Květa (advisor) ; Kubíčková, Anna (referee)
- 4 - Abstract in English This diploma thesis is focused on the evaluation and comparison of the enantioselective potential of two columns CHIRAL ART Amylose-SA and CDShell-RSP using a set of 29 chiral drugs in high performance liquid chromatography. The separations of enantiomers were performed in three modes: reversed-phase, normal-phase, and polar- organic mode. The CHIRAL ART Amylose-SA column was tested in normal-phase mode, the CDShell-RSP column in reversed-phase and polar-organic modes. The CHIRAL ART Amylose-SA column contains amylose tris(3,5- dimethylphenylcarbamate) immobilized on 3 µm porous silica gel particles. The CDShell-RSP column contains a chiral selector hydroxypropyl-β-cyclodextrin, which is covalently bonded on 2.7 µm superficially porous particles. In the normal-phase mode, mobile phases composed of hexane and propane-2-ol were used. Furthermore, the effect of various additives (triethylamine, diethylamine, trifluoroacetic acid, and the mixture of diethylamine and trifluoroacetic acid) in the mobile phase on the enantioseparation of chiral drugs was tested. The most universal additive was a mixture of diethylamine and trifluoroacetic acid. A total of 22 chiral drugs were enantioseparated on the CHIRAL ART Amylose-SA column, 10 of them were baseline separated. Mobile phases for...
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Enantioselective potential of sulfobutylether-β-cyclodextrin based chiral stationary phase
Folprechtová, Denisa ; Kalíková, Květa (advisor) ; Kubíčková, Anna (referee)
The aim of this diploma thesis was to prepare two new chiral stationary phases by dynamic coating of sulphobutylether-β-cyclodextrin (SBE-β-CD) with varying degrees of substitution onto strong anion-exchange stationary phases. The enantioselective potential and stability of the newly prepared chiral stationary phases were tested using a set of chiral analytes. The set contained structurally diverse analytes, i.e. benzodiazepines (oxazepam, lorazepam), phenothiazines (thioridazine, promethazine), β-blockers (labetalol, pindolol, propranolol, alprenolol), profens (carprofen, fenoprofen, flurbiprofen, indoprofen), flavanones (6-hydroxyflavanone, 7-hydroxyflavanone), DL-tryptophan and its derivatives (5-OH-DL-tryptophan, 5-F-DL-tryptophan, DL-tryptophan butylester and blocked aminoacid (t-Boc-DL-tryptophan)), dipeptides (glycyl-DL-phenylalanine, glycyl-DL-tryptophan) and Troger's base. Measurements were carried out in reversed-phase high-performance liquid chromatography. Mobile phases consisted of methanol/formic acid (pH 2.10) and methanol/10mmol l-1 ammonium acetate buffer (pH 4.00) in various volume ratios. The chiral stationary phase containing hexasubstituted SBE-β-CD was suitable for enantioseparation of eleven analytes. Four of them were baseline enantioresolved and seven partially. The chiral...
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Enantioselective separation of certain analytes using supercritical fluid chromatography and high performance liquid chromatography
Martínková, Monika ; Tesařová, Eva (advisor) ; Čabala, Radomír (referee)
(EN) Cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase was used for separation of selected 24 analytes. Enantioseparations were realized using two systems, high performance liquid chromatography and supercritical fluid chromatography. Effect of mobile phase composition was studied. Five different aditives (isopropylamine, diethylamine, triethylamine, trifluoroacetic acid, isopropylamine combined with trifluoroacetic acid) and their influence on enantioseparation were tested. Influence of two different modifiers (methanol, propan-2-ol) combined with all aditives was also tested in supercritical fluid chromatography system. The aim of this work was to find optimized composition of mobile phase which was suitable for separation of the analytes studied and to compare separation potential among all mobile phases and also between used separations systems. The supercritical fluid chromatography was shown to yield better results, i.e. better resolution in shorter analysis time. However examples of analytes better resolved under optimized conditions in high performance liquid chromatography system have also been found. Keywords (EN) Chirality, enantiomers, enantioselective separation, chiral stationary phase, high performance liquid chromatography, supercritical fluid chromatography.
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