Number of found documents: 542
Published from to

Separation of rotamers of 5-nitrosopyrimidines by capillary electrophoresis
Štěpánová, Sille; Procházková, Eliška; Čechová, Lucie; Žurek, Jiří; Janeba, Zlatko; Dračínský, Martin; Kašička, Václav
2018 - English
A new capillary electrophoresis (CE) method was developed for the separation of a new type of stereoisomers - rotamers of polysubstituted 5-nitrosopyrimidine derivatives. Partial separation of some rotamers was obtained in sodium borate, pH 9.3, or in Tris-phosphate, pH 2.2, background electrolytes (BGEs) free of cyclodextrins (CDs). However, the best, baseline separations of the rotamers of 5-nitrosopyrimidines were achieved in sodium borate BGE, pH 9.3, containing 20 mg/mL beta-CD as stereoselector, or in Tris-phosphate BGE, pH 2.2, with carboxymethyl-beta-CD as stereoselector. Keywords: rotamers; 5-nitrosopyrimidines; capillary electrophoresis Available at various institutes of the ASCR
Separation of rotamers of 5-nitrosopyrimidines by capillary electrophoresis

A new capillary electrophoresis (CE) method was developed for the separation of a new type of stereoisomers - rotamers of polysubstituted 5-nitrosopyrimidine derivatives. Partial separation of some ...

Štěpánová, Sille; Procházková, Eliška; Čechová, Lucie; Žurek, Jiří; Janeba, Zlatko; Dračínský, Martin; Kašička, Václav
Ústav organické chemie a biochemie, 2018

Ambientní ionizační techniky
Vrkoslav, Vladimír
2018 - Czech
V první část přednášky se zabývá vymezením pojmu ambientních ionizačních technika a rozdělením těchto technik. V další části byly vysvětleny principy nejdůležitějších ambientních ionizačních technika a bylo popsáno jejich využití. In the first part of the lecture definition and classification of ambient ionization techniques were described. In the next part the principles of the most important ambient ionization techniques were explained and their use was mentioned. Keywords: mass spectrometry Available at various institutes of the ASCR
Ambientní ionizační techniky

V první část přednášky se zabývá vymezením pojmu ambientních ionizačních technika a rozdělením těchto technik. V další části byly vysvětleny principy nejdůležitějších ambientních ionizačních technika ...

Vrkoslav, Vladimír
Ústav organické chemie a biochemie, 2018

Enantioseparation and estimation of racemization barriers of selected helquats and their derivatives by capillary electrophoresis using sulfated cyclodextrins as chiral selectors
Sázelová, Petra; Koval, Dušan; Severa, Lukáš; Reyes Gutierrez, Paul Eduardo; Jirásek, Michael; Teplý, Filip; Kašička, Václav
2018 - English
Anionic highly sulfated β- and γ-cyclodextrins (S-CDs) and single-isomer heptakis-(2,3-diacetyl-6-sulfato)-β-CD (14Ac-7S-β-CD) were used for chiral separation of [5], [6] and [7]-ring helquats and helquat styryl dyes by capillary electrophoresis (CE) in the background electrolyte composed of 22 mM NaOH/35 mM H3PO4, pH 2.4. The CE method was applied for monitoring of racemization of eight helquats and helical dyes. Rate constant k of conversion, half-life T1/2 of racemization, and activation Gibbs free energy ΔGǂ of interconversion of one enantiomer into the other were calculated from the dependence of natural logarithm of enantiomeric excess (ee) on time using linear regression analysis. Keywords: helquats; racemization barrier; capillary electrophoresis Fulltext is available at external website.
Enantioseparation and estimation of racemization barriers of selected helquats and their derivatives by capillary electrophoresis using sulfated cyclodextrins as chiral selectors

Anionic highly sulfated β- and γ-cyclodextrins (S-CDs) and single-isomer heptakis-(2,3-diacetyl-6-sulfato)-β-CD (14Ac-7S-β-CD) were used for chiral separation of [5], [6] and [7]-ring helquats and ...

Sázelová, Petra; Koval, Dušan; Severa, Lukáš; Reyes Gutierrez, Paul Eduardo; Jirásek, Michael; Teplý, Filip; Kašička, Václav
Ústav organické chemie a biochemie, 2018

Determination of Bitrex in conifer needles using capillary electrophoresis
Jaklová Dytrtová, Jana; Jakl, M.; Konášová, Renáta; Kašička, Václav
2018 - English
Two extraction procedures have been developed for the sample preparation regarding the determination of Bitrex (Denatonium benzoate) on the surface of conifer needles (1) and in the biomass of the chopped conifer needles (2). The content of the Bitrex in the extracts was determined by capillary electrophoresis with UV-absorption photometric detection. The recovery of Bitrex from the needle surface is 90%, however the procedure designed for determination of Bitrex from needles is not sufficient, because the recovery is only 30 %. Keywords: denatonium benzoate; needle extracts; capillary electrophoresis Available at various institutes of the ASCR
Determination of Bitrex in conifer needles using capillary electrophoresis

Two extraction procedures have been developed for the sample preparation regarding the determination of Bitrex (Denatonium benzoate) on the surface of conifer needles (1) and in the biomass of the ...

Jaklová Dytrtová, Jana; Jakl, M.; Konášová, Renáta; Kašička, Václav
Ústav organické chemie a biochemie, 2018

Estimation of binding constants of associates of Ru(II) and Fe(II) polypyridyl complexes with single-isomer sulfated cyclodextrins by capillary electrophoresis
Sázelová, Petra; Koval, Dušan; Severa, Lukáš; Teplý, Filip; Kašička, Václav
2018 - English
Capillary electrophoresis (CE) was applied for enantioseparations of [Ru(bpy)3]2+, [Ru(phen) 3]2+ and [Fe(phen) 3]2+ complexes and for the estimation of binding constants of their associates with selected single-isomer sulfated cyclodextrins (SCDs). The apparent binding constants of the complexes of [Ru(bpy)3]2+, [Ru(phen)3]2+, and [Fe(phen)3]2+ enantiomers with the above SCDs were determined from the dependence of their effective electrophoretic mobilities on the concentration of the SCDs in the background electrolyte. Calculated apparent binding constants were found to be smaller than those obtained for randomly sulfated SCDs. Keywords: polypyridyl complexes; stability constant; capillary electrophoresis Available at various institutes of the ASCR
Estimation of binding constants of associates of Ru(II) and Fe(II) polypyridyl complexes with single-isomer sulfated cyclodextrins by capillary electrophoresis

Capillary electrophoresis (CE) was applied for enantioseparations of [Ru(bpy)3]2+, [Ru(phen) 3]2+ and [Fe(phen) 3]2+ complexes and for the estimation of binding constants of their associates with ...

Sázelová, Petra; Koval, Dušan; Severa, Lukáš; Teplý, Filip; Kašička, Václav
Ústav organické chemie a biochemie, 2018

Iontové zdroje pro LC/MS
Cvačka, Josef
2018 - Czech
Byly popsány iontové zdroje, které se používají pro spojení kapalinového chromatografu s hmotnostním spektrometrem. The ion sources used for conection of liquid chromatograph and the mass spectrometer were described. Keywords: mass spectrometry; ionization Available at various institutes of the ASCR
Iontové zdroje pro LC/MS

Byly popsány iontové zdroje, které se používají pro spojení kapalinového chromatografu s hmotnostním spektrometrem....

Cvačka, Josef
Ústav organické chemie a biochemie, 2018

Penconazole and its behaviour in the presence of copper
Jakl, M.; Jaklová Dytrtová, Jana
2018 - English
Penconazole is a fungicide frequently used in agriculture. Its possible impact to (non-)target species is influenced by its interactions e.g. with copper, typically present in soil as an ion (or in week complexes) or in bodies, as a part of enzymes. This study brings the information potentially useful in the evaluation of penconazole fate in the environment. The studies based on the electrospray gas phase experiments provide an estimate of the penconazole reactivity in copper presence including its possible degradation pathways. Keywords: triazoles; Cu(II); Cu(I); mass spectrometry; ESI-MS; stability; degradation Available at various institutes of the ASCR
Penconazole and its behaviour in the presence of copper

Penconazole is a fungicide frequently used in agriculture. Its possible impact to (non-)target species is influenced by its interactions e.g. with copper, typically present in soil as an ion (or in ...

Jakl, M.; Jaklová Dytrtová, Jana
Ústav organické chemie a biochemie, 2018

Determination of binding constants of human insulin complexes with serotonin, dopamine, arginine, and phenol by pressure assisted partial filling affinity capillary electrophoresis
Šolínová, Veronika; Žáková, Lenka; Jiráček, Jiří; Kašička, Václav
2018 - English
A new method, pressure assisted partial filling affinity capillary electrophoresis (PF-ACE), has been developed to study noncovalent interactions of the hexamer of human insulin (HI) with cationic ligands, such as phenolic neurotransmitters serotonin and dopamine, and amino acid arginine, or with anionic ligand phenol, in alkaline aqueous solutions. The apparent binding constants, Kb, of the HI-ligand complexes were determined from the dependence of the effective migration time changes of the above ligands on the variable zone lengths of HI dissolved in the background electrolyte and hydrodynamically introduced into the bare fused silica capillary close to the UV detector. The HI interactions with the above ligands were found to be moderately strong, with Kb values in the range 385-1314 L/mol. Keywords: human insulin; ligand; affinity capillary electrophoresis Fulltext is available at external website.
Determination of binding constants of human insulin complexes with serotonin, dopamine, arginine, and phenol by pressure assisted partial filling affinity capillary electrophoresis

A new method, pressure assisted partial filling affinity capillary electrophoresis (PF-ACE), has been developed to study noncovalent interactions of the hexamer of human insulin (HI) with cationic ...

Šolínová, Veronika; Žáková, Lenka; Jiráček, Jiří; Kašička, Václav
Ústav organické chemie a biochemie, 2018

Temperature-programed micro-HPLC analysis of fatty acid methyl esters with APCI-MS detection
Vrkoslav, Vladimír; Rumlová, Barbora; Cvačka, Josef
2018 - English
HPLC/APCI-MS analysis at microliters-per-minute flow rates was optimized for separation of fatty acid methyl esters (FAMEs). HPLC C18 column with an internal diameter of 0.3 mm and isocratic elution using 99.9 % acetonitrile and 0.1% formic acid were employed. Standard APCI ion source was suitable for detection of FAMEs at 10 μl/min flow rate with the detection limit of micrograms-per-milliliter. APCI-MS spectra with predominant [M + H]+ molecular adducts were observed. The main advantage of micro-flow measurements is the possibility of using a temperature gradient, which significantly reduces retention times of FAMEs with longer aliphatic chain. The significant reduction of solvent consumption is also an important economic and environmental advantage. The positions of double bonds in FAME chains were established using acetonitrile-related adducts and tandem mass spectrometry. The optimized method was applied for analysis of FAMEs in triacylglycerol fraction of black currant seeds oil. Keywords: liquid chromatography; mass spectrometry; atmospheric pressure chemical ionization Fulltext is available at external website.
Temperature-programed micro-HPLC analysis of fatty acid methyl esters with APCI-MS detection

HPLC/APCI-MS analysis at microliters-per-minute flow rates was optimized for separation of fatty acid methyl esters (FAMEs). HPLC C18 column with an internal diameter of 0.3 mm and isocratic elution ...

Vrkoslav, Vladimír; Rumlová, Barbora; Cvačka, Josef
Ústav organické chemie a biochemie, 2018

Development of a tube nebulizer for microflow atmospheric pressure chemical ionization mass spectrometry
Strmeň, Timotej; Vrkoslav, Vladimír; Pačes, Ondřej; Cvačka, Josef
2017 - English
A novel nebulizer for microflow atmospheric pressure chemical ionization mass spectrometry was developed. It consisted of a tube with analyte-transporting fused silica capillary inside. The terminal part of the tube was resistively heated using a coiled resistance wire. Optimal nebulizer parameters and construction setup were investigated to fully demonstrate its versability. Corundum appeared to be a more suitable material than quartz for fabrication of the tube nebulizer. The lowest analyte flow rate investigated was 1.0 mul/min with an excellent signal stability reached. Keywords: mass spectrometry; micro-APCI; tube nebulizer Available at various institutes of the ASCR
Development of a tube nebulizer for microflow atmospheric pressure chemical ionization mass spectrometry

A novel nebulizer for microflow atmospheric pressure chemical ionization mass spectrometry was developed. It consisted of a tube with analyte-transporting fused silica capillary inside. The terminal ...

Strmeň, Timotej; Vrkoslav, Vladimír; Pačes, Ondřej; Cvačka, Josef
Ústav organické chemie a biochemie, 2017

About project

NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web

Send your suggestions and comments to nusl@techlib.cz

Provider

http://www.techlib.cz

Facebook

Other bases