Number of found documents: 545
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Mimikování metabolismu thiramu pomocí elektrochemie spojené s hmotnostní spektrometrií
Jaklová Dytrtová, Jana; Jakl, M.
2016 - Czech
On-line zapojení elektrochemické cely vlastní výroby před hmotnostní spektrometr s ionizací elektrosprejem (EC-ESI-MS) bylo studováno pro možné využití při simulaci metabolismu thiramu (T). Instrumentační přístup EC-ESI-MS potvrzuje vytvoření prvního metabolického produktu T (Tm). Tm se tvoří rozpadem disulfidové vazby. Je diskutován katalytický účinek mědi pocházející z měděné pracovní elektrody na tuto reakci. On-line hyphenation of a home-made electrochemical cell with an electrospray ionization mass spectrometer (EC-ESI-MS) was investigated to be applicable in mimicking of thiram (T) metabolism. The EC-ESI-MS instrumental approach confirms the creation of the first metabolic product of T (Tm). Tm is created via the decay of the disulfide bond. The catalytic effect of copper originated from the copper working electrode to this reaction is discussed. Keywords: cytochrome P450; oxidation; reduction; lab-on-chip; ex situ Available at various institutes of the ASCR
Mimikování metabolismu thiramu pomocí elektrochemie spojené s hmotnostní spektrometrií

On-line zapojení elektrochemické cely vlastní výroby před hmotnostní spektrometr s ionizací elektrosprejem (EC-ESI-MS) bylo studováno pro možné využití při simulaci metabolismu thiramu (T). ...

Jaklová Dytrtová, Jana; Jakl, M.
Ústav organické chemie a biochemie, 2016

Mobilization of neutral compounds by inorganic and small organic ions in capillary electrophoresis
Křížek, T.; Martínková, E.; Kubíčková, A.; Hladílková, Jana; Coufal, P.; Heyda, J.; Jungwirth, Pavel
2016 - English
The present study shows that neutral low-molecular-mass compounds that are presumed to possess zero electrophoretic mobility and are thus used as markers of electroosmotic flow in capillary electrophoresis can acquire electrophoretic mobility due to ion-specific interactions with constituents of background electrolyte. Therefore, these neutral markers, such as thiourea or dimethyl sulfoxide, can be separated in electric field and their migration order can vary depending on background electrolyte composition. This observation has some important implications for analytical and physico-chemical measurements using capillary electrophoresis because the choice of the marker-background electrolyte combination can influence the results of the measurement. Keywords: capillary electrophoresis; EOF markers; ion-specific effects; mobilization Available at various institutes of the ASCR
Mobilization of neutral compounds by inorganic and small organic ions in capillary electrophoresis

The present study shows that neutral low-molecular-mass compounds that are presumed to possess zero electrophoretic mobility and are thus used as markers of electroosmotic flow in capillary ...

Křížek, T.; Martínková, E.; Kubíčková, A.; Hladílková, Jana; Coufal, P.; Heyda, J.; Jungwirth, Pavel
Ústav organické chemie a biochemie, 2016

Investigation of calix[4]arene-bis(t-octylbenzo-18-crown-6) complex with cesium cation by affinity capillary electrophoresis
Štěpánová, Sille; Moyer, B.; Makrlík, E.; Kašička, Václav
2016 - English
Affinity capillary electrophoresis (ACE) was employed for investigation of non-covalent interactions of calix[4]arene-bis(t-octylbenzo-18-crown-6) with Cs+ ion in methanol. The apparent binding constant of the calix[4]arene-bis(t-octylbenzo-18-crown-6)-Cs+ complex was determined from the dependence of the effective electrophoretic mobilities of the calix[4]arene-bis(t-octylbenzo-18-crown-6) on the concentration of cesium ion in the backround electrolyte using a non-linear regression analysis. The logarithmic form of the conditional apparent binding constant of calix[4]arene-bis(t-octylbenzo-18-crown-6)-Cs+ complex was found to be equal to 1.61. Keywords: affinity capillary electrophoresis; calix[4]arene-bis(t-octylbenzo-18-crown-6); binding constant Available at various institutes of the ASCR
Investigation of calix[4]arene-bis(t-octylbenzo-18-crown-6) complex with cesium cation by affinity capillary electrophoresis

Affinity capillary electrophoresis (ACE) was employed for investigation of non-covalent interactions of calix[4]arene-bis(t-octylbenzo-18-crown-6) with Cs+ ion in methanol. The apparent binding ...

Štěpánová, Sille; Moyer, B.; Makrlík, E.; Kašička, Václav
Ústav organické chemie a biochemie, 2016

Determination of stability constant of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents by affinity capillary electrophoresis
Konášová, Renáta; Jaklová Dytrtová, Jana; Kašička, Václav
2016 - English
Affinity capillary electrophoresis was applied to determination of apparent stability constant, Kst, of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents, i.e. mixtures of water with methanol, ethanol, propan-2-ol or acetonitrile. It was found that the Kst strongly depends on the solvent composition. The log Kst values linearly increase with decreasing molar fraction of water in the above hydro-organic solvent mixture. Keywords: affinity capillary electrophoresis; dibenzo-18-crown-6; stability constant Available at various institutes of the ASCR
Determination of stability constant of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents by affinity capillary electrophoresis

Affinity capillary electrophoresis was applied to determination of apparent stability constant, Kst, of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents, i.e. mixtures of water ...

Konášová, Renáta; Jaklová Dytrtová, Jana; Kašička, Václav
Ústav organické chemie a biochemie, 2016

Frustrated Lewis pairs-assisted reduction of carbonyl compounds
Marek, Aleš; Pedersen, M. H. F.
2016 - English
An alternative and robust method for the reduction of carbonyl groups by frustrated Lewis pairs (FLPs) is reported in this paper. With its very mild reaction conditions, good to excellent yields, absolute regioselectivity and the non-metallic character of the reagent, it provides an excellent tool for 1H, 2H as well as 3H chemistry. It is a new strategy for the one-pot synthesis of aromatic alcohols selectively labeled with heavy isotopes of hydrogen. Keywords: carbonyl compounds; frustrated Lewis parts; alcohol synthesis Available at various institutes of the ASCR
Frustrated Lewis pairs-assisted reduction of carbonyl compounds

An alternative and robust method for the reduction of carbonyl groups by frustrated Lewis pairs (FLPs) is reported in this paper. With its very mild reaction conditions, good to excellent yields, ...

Marek, Aleš; Pedersen, M. H. F.
Ústav organické chemie a biochemie, 2016

Analysis of novel members of FAHFA lipid class derived from omega 3-PUFA by LC-MS/MS and LC-MS/MS/MS
Rombaldová, Martina; Kuda, Ondřej; Březinová, Marie; Slavíková, Barbora; Pošta, Martin; Beier, Petr; Janovská, Petra; Veleba, J.; Kopecký Jr., J.; Kudová, Eva; Pelikánová, T.; Kopecký, Jan
2016 - English
White adipose tissue (WAT) is a complex organ with both metabolic and endocrine functions. Dysregulation of all of these functions of WAT, together with low-grade inflammation of the tissue in obesity, contributes to the development of insulin resistance and type 2 diabetes. Omega-3 polyunsaturated fatty acids (PUFA) of marine origin play an important role in resolution of inflammation and exert beneficial metabolic effects. Using LC-MS/MS method, we elucidated the structures of novel members of fatty acid esters of hydroxy fatty acids (FAHFA), which were present in murine and human serum and WAT after omega-3 PUFA supplementation in diet. These compounds contained DHA esterified to 9- and 13-hydroxyoctadecadienoic acid (HLA) termed 9-DHAHLA and 13-DHAHLA, and were synthesized in WAT. Our results document the existence of novel lipid mediators, which are involved in the beneficial anti-inflammatory effects attributed toomega-3 PUFA, in both miceandhumans. Keywords: branched fatty acid; lipidomics; mass spectrometry; omega 3-PUFA Available at various institutes of the ASCR
Analysis of novel members of FAHFA lipid class derived from omega 3-PUFA by LC-MS/MS and LC-MS/MS/MS

White adipose tissue (WAT) is a complex organ with both metabolic and endocrine functions. Dysregulation of all of these functions of WAT, together with low-grade inflammation of the tissue in ...

Rombaldová, Martina; Kuda, Ondřej; Březinová, Marie; Slavíková, Barbora; Pošta, Martin; Beier, Petr; Janovská, Petra; Veleba, J.; Kopecký Jr., J.; Kudová, Eva; Pelikánová, T.; Kopecký, Jan
Ústav organické chemie a biochemie, 2016

Enantioseparations of drugs and catalysts by partial-filling affinity capillary electrophoresis using helquats as chiral selectors
Růžička, Martin; Koval, Dušan; Vávra, Jan; Reyes Gutierrez, Paul Eduardo; Teplý, Filip; Kašička, Václav
2016 - English
Noncovalent molecular interactions between helquats, a new class of dicationic helical extended diquats and selected commonly used negatively charged chiral drugs and catalysts have been investigated using partial-filling affinity capillary electrophoresis (PF-ACE). Three types of interactions of analytes with helquats were observed: (1) medium strong enantioselective interactions, (2) medium strong non-enantioselective interactions and (3) no or very weak non-enantioselective interactions. Keywords: affinity capillary electrophoresis; helquats; chiral selector Available at various institutes of the ASCR
Enantioseparations of drugs and catalysts by partial-filling affinity capillary electrophoresis using helquats as chiral selectors

Noncovalent molecular interactions between helquats, a new class of dicationic helical extended diquats and selected commonly used negatively charged chiral drugs and catalysts have been investigated ...

Růžička, Martin; Koval, Dušan; Vávra, Jan; Reyes Gutierrez, Paul Eduardo; Teplý, Filip; Kašička, Václav
Ústav organické chemie a biochemie, 2016

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
2016 - English
The recently developed capillary electrophoretic (CE) method for chiral analysis of helquats (helical N-heteroaromatic dications) was applied to monitoring of racemization of selected helquats and helquat styryl dyes and for the determination of their racemization barriers, i.e. activation Gibbs free energy deltaG≠. deltaG≠ of analyzed compounds was found to be in the range 107.7 – 115.7 kJ/mol. Keywords: capillary electrophoresis; helquats; interconversion barrier Available at various institutes of the ASCR
Estimation of racemization barriers of selected helquats and their derivatives by capillary electrophoresis using sulfated cyclodextrins as chiral selectors

The recently developed capillary electrophoretic (CE) method for chiral analysis of helquats (helical N-heteroaromatic dications) was applied to monitoring of racemization of selected helquats and ...

Sázelová, Petra; Koval, Dušan; Severa, Lukáš; Reyes Gutierrez, Paul Eduardo; Jirásek, Michael; Teplý, Filip; Kašička, Václav
Ústav organické chemie a biochemie, 2016

Stanovení prvků v rostlinných materiálech metodou optické emisní spektrometrie s indukčně vázaným plazmatem a elektrotermickým odpařováním
Šerá, Luisa; Matějková, Stanislava; Mestek, O.
2016 - Czech
Podařilo se vyvinout vhodnou analytickou metodu ICP-OES analýzy ve spojení s ETV pro rychlou kvantitativní analýzu rostlinných makro- i mikrobiogenních prvků. Pro tuto metodu byl zvolen plynný modifikátor, optimalizován teplotní program a zvoleny sledované spektrální čáry. U většiny těchto čar byla pomocí Mandelova testu linearity ověřena lineární kalibrační závislost intenzity signálu na množství analytu, u ostatních byla použita závislost kvadratická. Dále byly pro všechny spektrální čáry určeny LOD ze slepých pokusů. Také byl sledován vliv velikosti navážky vzorku na přesnost měření, kde optimální se jeví navážky mezi jedním a dvěma miligramy, v závislosti na očekávaném obsahu analytů ve vzorku. Analýzou CRM INCT-OBTL-5 Tabákových listů byla u 7 ze 12 stanovovaných analytů testem výtěžnosti potvrzena přesnost vyvinuté metody. I tak byla u většiny analytů zjištěna odchylka mezi certifikovanou a naměřenou hodnotou obsahu analytu v CRM do deseti procent, což je srovnatelné s publikovanými výsledky a s požadavky běžně kladenými na použitou metodu. Dalším cílem výzkumu bude posouzení vlivu průtoku nosného a „bypass“ plynu na průběh a přesnost analýzy. Dále se pokusíme vyzkoušet současné zapojení ETV a zmlžovače jako zdroje signálu interního standardu a posoudit vliv takového zapojení na průběh analýzy a její výsledky. This paper describes optimization and validation of operating conditions of electrothermal vaporization (ETV) inductively coupled plasma optical emission spectrometry (ICP-OES) method for quantification of Ba, Ca, Co, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn in plant materials. Besides the optimization of the temperature program, the selection of the gaseous modifier and the spectral wavelengths to be measured, it was studied how the sample quantity affects the result quality of the developed method. During the validation process, the accuracy and precision of the method were checked by analysis of a certified reference material. Limits of detection were estimated by analyses of blank samples. For almost all previously mentioned elements, the method meets requirements commonly applied on analyses by ETV combined with ICP-OES. Keywords: electrothermal vaporization; optical emission spectrometry; inductively coupled plasma; plants Available at various institutes of the ASCR
Stanovení prvků v rostlinných materiálech metodou optické emisní spektrometrie s indukčně vázaným plazmatem a elektrotermickým odpařováním

Podařilo se vyvinout vhodnou analytickou metodu ICP-OES analýzy ve spojení s ETV pro rychlou kvantitativní analýzu rostlinných makro- i mikrobiogenních prvků. Pro tuto metodu byl zvolen plynný ...

Šerá, Luisa; Matějková, Stanislava; Mestek, O.
Ústav organické chemie a biochemie, 2016

ICP-OES s elektrotermickou vaporizací (ETV) a příklad využití metody při přímé analýze biologických vzorků
Matějková, Stanislava
2015 - Czech
Optická spektrometrie s indukčně vázaným plasmatem a elektrotermickou vaporizací (ETV-ICP-OES) je metodou umožňující jednoduché a rychlé přímé stanovení makro-, mikro- i stopových prvků v pevných i kapalných vzorcích bez předchozí úpravy. Metoda snižuje riziko kontaminace vzorků a vzhledem k vysoké efektivitě přenosu analytů do plasmatu je možno provádět analýzu z velmi malého množství vzorků (jednotky mg). V naší laboratoři byla vyvinuta metoda pro sledování hladiny a chování derivátů karboranů v organismu na základě stanovení koncentrace boru a kobaltu v malých množstvích myších tkání (5 – 10 mg séra, jater mebo mozku). Solid sampling electrothermal vaporization (ETV) inductively coupled plasma optical emission spectroscopy (ICP-OES) enable simple and rapid multielemental analysis of major, minor and trace elements without the need for pre-treatment of solid or liquid samples. By comparison with more common ICP-OES combined with a solution nebulization, the risk of contamination of analysed samples is reduced. The detection limits and the sample quantity needed for analysis via ETV-ICP-OES decrease as a result of the high-efectivity transport of the sample aerosol into the ICP torch. The connection of ETV unit to simultaneous ICP-OES allows us the fast direct and fully automatised analysis of numerous samples. The technique enable usually the combined calibration with home-made or certified solid and aqueous standards. We developed the methodology for tracking the carboran-based candidate-drugs time dependent concentration and for their pharmacokinetic evaluation. The method is based on direct boron or together boron and cobalt contents direct estimation in little amounts of fresh frozen mice tissues (5 – 10 mg of serum, brain or liver).\n Keywords: ETV-ICP-OES; biological samples; multielemental analysis Available at various institutes of the ASCR
ICP-OES s elektrotermickou vaporizací (ETV) a příklad využití metody při přímé analýze biologických vzorků

Optická spektrometrie s indukčně vázaným plasmatem a elektrotermickou vaporizací (ETV-ICP-OES) je metodou umožňující jednoduché a rychlé přímé stanovení makro-, mikro- i stopových prvků v pevných i ...

Matějková, Stanislava
Ústav organické chemie a biochemie, 2015

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