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Determination of inositol in medicinal products by HPLC
Rážová, Michaela ; Odehnalová,, Klára (referee) ; Pazourek,, Jiří (advisor)
This work focuses on the determination of inositol in drugs and food supplements using high-performance liquid chromatography in HILIC mode. The work is divided into several sections, it discusses the characteristics of analyzed myo-inositol including methods for saccharides determination. A chapter is detached for high-performance liquid chromatography. One of the work goals was also chromatography columns comparison. The experimental part includes measurement conditions, methods of sample preparation evaluated data and results including the discussion. Two real samples were analyzed, in both of them the content of myo-inositol was declared by the producer.
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Characterization of new HILIC stationary phases
Vaclová, Jana
Hydrophilic interaction liquid chromatography is a frequently used separation method for analysis of polar compounds. It is an alternative method to reversed-phase chromatography, where these compounds show insufficient or very weak retention. A high number of stationary phases are currently available for HILIC and new ones are still being developed. The aim of this diploma thesis was to characterize and compare three relatively new HILIC columns containing an unmodified silica gel (HILIC-A), aminopropyl modified silica (HILIC-B) and polyhydroxyl chain modified silica (HILIC-N) as stationary phase. Based on the study of the effect of acetonitrile content in mobile phase on the retention of a model set of peptides, a multimodal retention mechanism was demonstrated. Analysis of 18 model analytes with different pKa values showed, that the composition of aqueous part of mobile phase (buffer), more specifically it's concentration and pH value, has a significant impact on retention of ionized analytes and peptides on the studied stationary phases. A significant contribution of ionic interactions to retention was observed on HILIC-B and HILIC-A columns. The retention of basic compounds on the HILIC-B column increased with increasing ionic strength, while it decreased on the HILIC-A column. Increasing the...
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Characterization of new HILIC stationary phases
Vaclová, Jana ; Kozlík, Petr (advisor) ; Kubíčková, Anna (referee)
Hydrophilic interaction liquid chromatography is a frequently used separation method for analysis of polar compounds. It is an alternative method to reversed-phase chromatography, where these compounds show insufficient or very weak retention. A high number of stationary phases are currently available for HILIC and new ones are still being developed. The aim of this diploma thesis was to characterize and compare three relatively new HILIC columns containing an unmodified silica gel (HILIC-A), aminopropyl modified silica (HILIC-B) and polyhydroxyl chain modified silica (HILIC-N) as stationary phase. Based on the study of the effect of acetonitrile content in mobile phase on the retention of a model set of peptides, a multimodal retention mechanism was demonstrated. Analysis of 18 model analytes with different pKa values showed, that the composition of aqueous part of mobile phase (buffer), more specifically it's concentration and pH value, has a significant impact on retention of ionized analytes and peptides on the studied stationary phases. A significant contribution of ionic interactions to retention was observed on HILIC-B and HILIC-A columns. The retention of basic compounds on the HILIC-B column increased with increasing ionic strength, while it decreased on the HILIC-A column. Increasing the...
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Separation of phospholipids by high pressure liquid chromatography
Erdeová, Karolína ; Čabala, Radomír (advisor) ; Sobotníková, Jana (referee)
Fosfolipidy jsou součástí buněčných membrán všech živých organismů. Jedná se o nejvýznamnější skupinu polárních lipidů, vyznačující se amfifilními vlastnostmi. Tyto vlastnosti vyplývají z jejich molekulární struktury, která se skládá z hydrofobních mastných řetězců a polární hlavice. Podle polární hlavice se dělí fosfolipidy do příslušných tříd. Poměr fosfolipidových tříd, zastoupených v bakteriální membráně, značně odráží životní pochody mikroorganismu. Pomocí změn v zastoupení těchto tříd lze sledovat vliv vnějšího prostředí, čehož se využívá v mikrobiologickém výzkumu. Pro sledování fosfolipidového složení vyšlechtěného kmene Bacillus subtilis, který je intenzivně zkoumán pro produkci antibiotik, se stále využívá tenkovrstvá chromatografie. Její časová náročnost výzkum značně zpomaluje, a proto byly podmínky tohoto uspořádání přeneseny na HPLC. Pro tyto účely byla metoda optimalizována formou nelineárního gradientu. Vhodnost metody byla testována na vzorku bakteriálních membránových lipidů, který obsahoval pět fosfolipidových tříd, z čehož dvě majoritní. Jejich poměrné zastoupení lze stanovit, nicméně je nutno pečlivě volit objem nastřikovaného vzorku, aby se zabránilo překročení úzkého koncentračního rozsahu metody. Klíčová slova: fosfolipidy, HPLC, optimalizace, validace, HILIC, NP-HPLC
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Characterization of novel stationary phase in hydrophilic interaction liquid chromatography
Kadlecová, Zuzana ; Kalíková, Květa (advisor) ; Kozlík, Petr (referee)
The aim of this diploma thesis is detailed characterization of new diol-based column, i.e. Torus DIOL designed for supercritical fluid chromatography, in hydrophilic interaction liquid chromatography. This stationary phase contains diol ligands bonded on BEH ("bridged ethylene hybrid") particles. The BEH sorbent is more stable at high pH, pressure and temperature than conventional silica sorbents. Five fluorinated pesticides were successfully separated on Torus DIOL column. Retention mechanism and effect of different parameters were tested by analysis of small polar compounds (nucleobases, uridine and its derivatives, acidic, neutral and basic compounds). Both partitioning of analytes between an aqueous layer deposited on the surface of the stationary phase and the mobile phase and adsorption of analytes on the stationary phase participate in the retention mechanism. Effect of the mobile phase aqueous part pH was investigated with the following buffering solutions: formic acid (pH = 2.1), 10mM ammonium acetate (pH = 4.7 and pH = 9.5). Obtained results showed that aqueous part pH significantly affects retention of acidic compounds according to their pKA values. Retention of all tested analytes on Torus DIOL column slightly increased with increasing ionic strength of mobile phase. The retention...
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Development of a novel method for nucleotide pool analysis in bacterial cells
Zborníková, Eva ; Rejman, Dominik (advisor) ; Pacáková, Věra (referee) ; Kozlík, Petr (referee)
(EN) This thesis deals with the determination of nucleotides in bacterial cells. Nucleotides play crucial role in most of the metabolic pathway. Determining their concentrations could give us important clues about the influence of internal and external conditions on the bacterial metabolism. Previously published papers dealing with the analysis of nucleotides and other intracellular metabolites can be divided into two groups according to the analytical approach: a) metabolomic approach and b) targeted approach dealing with narrow group of target analytes. In the case a) most authors use the state-of-the-art LC-MS/MS technique, whereas in the case b) robust UV detection coupled mainly to IP-LC is widely used. The aim of this study was to combine both approaches to obtain a method for routine analysis that would take advantages of mass detection, such as sensitivity and selectivity, while avoiding the need of demanding optimization of MS/MS transitions and expert service. The main purpose of the newly developed HILIC-MS method is its universal applicability in most biological and biochemical laboratories.
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Characterization of new HILIC stationary phases
Vaclová, Jana ; Kozlík, Petr (advisor) ; Kubíčková, Anna (referee)
Hydrophilic interaction liquid chromatography is a frequently used separation method for analysis of polar compounds. It is an alternative method to reversed-phase chromatography, where these compounds show insufficient or very weak retention. A high number of stationary phases are currently available for HILIC and new ones are still being developed. The aim of this diploma thesis was to characterize and compare three relatively new HILIC columns containing an unmodified silica gel (HILIC-A), aminopropyl modified silica (HILIC-B) and polyhydroxyl chain modified silica (HILIC-N) as stationary phase. Based on the study of the effect of acetonitrile content in mobile phase on the retention of a model set of peptides, a multimodal retention mechanism was demonstrated. Analysis of 18 model analytes with different pKa values showed, that the composition of aqueous part of mobile phase (buffer), more specifically it's concentration and pH value, has a significant impact on retention of ionized analytes and peptides on the studied stationary phases. A significant contribution of ionic interactions to retention was observed on HILIC-B and HILIC-A columns. The retention of basic compounds on the HILIC-B column increased with increasing ionic strength, while it decreased on the HILIC-A column. Increasing the...
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Development of a novel method for nucleotide pool analysis in bacterial cells
Zborníková, Eva ; Rejman, Dominik (advisor) ; Pacáková, Věra (referee) ; Kozlík, Petr (referee)
(EN) This thesis deals with the determination of nucleotides in bacterial cells. Nucleotides play crucial role in most of the metabolic pathway. Determining their concentrations could give us important clues about the influence of internal and external conditions on the bacterial metabolism. Previously published papers dealing with the analysis of nucleotides and other intracellular metabolites can be divided into two groups according to the analytical approach: a) metabolomic approach and b) targeted approach dealing with narrow group of target analytes. In the case a) most authors use the state-of-the-art LC-MS/MS technique, whereas in the case b) robust UV detection coupled mainly to IP-LC is widely used. The aim of this study was to combine both approaches to obtain a method for routine analysis that would take advantages of mass detection, such as sensitivity and selectivity, while avoiding the need of demanding optimization of MS/MS transitions and expert service. The main purpose of the newly developed HILIC-MS method is its universal applicability in most biological and biochemical laboratories.
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Characterization of novel stationary phase in hydrophilic interaction liquid chromatography
Kadlecová, Zuzana ; Kalíková, Květa (advisor) ; Kozlík, Petr (referee)
The aim of this diploma thesis is detailed characterization of new diol-based column, i.e. Torus DIOL designed for supercritical fluid chromatography, in hydrophilic interaction liquid chromatography. This stationary phase contains diol ligands bonded on BEH ("bridged ethylene hybrid") particles. The BEH sorbent is more stable at high pH, pressure and temperature than conventional silica sorbents. Five fluorinated pesticides were successfully separated on Torus DIOL column. Retention mechanism and effect of different parameters were tested by analysis of small polar compounds (nucleobases, uridine and its derivatives, acidic, neutral and basic compounds). Both partitioning of analytes between an aqueous layer deposited on the surface of the stationary phase and the mobile phase and adsorption of analytes on the stationary phase participate in the retention mechanism. Effect of the mobile phase aqueous part pH was investigated with the following buffering solutions: formic acid (pH = 2.1), 10mM ammonium acetate (pH = 4.7 and pH = 9.5). Obtained results showed that aqueous part pH significantly affects retention of acidic compounds according to their pKA values. Retention of all tested analytes on Torus DIOL column slightly increased with increasing ionic strength of mobile phase. The retention...
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