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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 ...
Charge Transport through Molecular Towers Based on Tetraphenylmethane Tripods
Kolivoška, V.; Šebera, Jakub; Lindner, M.; Valášek, M.; Mayor, M.; Mészáros, G.; Gasior, J.; Hromadová, M.
2017 - English
Molecular platforms with multiple anchors were introduced recently to provide robust coupling between molecular electronic components and metallic electrodes. In this work, charge transport in tower-shaped single molecule conductors based on tetraphenylmethane tripod possessing three thiol anchors is investigated by scanning tunneling microscopy break junction technique. The effect of tripod substitution pattern and number of repeating units in molecule is addressed. The substitution was found to influence conductance value in early stages of molecular junction evolution, where tower lays parallel to surface. In late stages, the charge is transported through principal molecular axis and junction breaks thermally in tilted configuration.
Keywords:
charge transport through single molecules; break junction technique; molecular electronics
Available at various institutes of the ASCR
Charge Transport through Molecular Towers Based on Tetraphenylmethane Tripods
Molecular platforms with multiple anchors were introduced recently to provide robust coupling between molecular electronic components and metallic electrodes. In this work, charge transport in ...
Capillary isotachophoresis and zone electrophoresis applied to determination of effective charge of polyelectrolytes
Kašička, Václav; Koval, Dušan; Ibrahim, A.; Chamieh, J.; Cottet, H.
2016 - English
Capillary electromigration methods, isotachophoresis (CITP) and zone electrophoresis (CZE) were applied to determination of effective charge of poly-alpha-L-glutamic acid and poly-alpha-L-lysine using both CITP-dedicated device and common CZE apparatus. Combination of CITP and CZE methods in both these types of devices proved to be a suitable platform for determination of effective charge of a wide range of polyelectrolytes – weak and strong, polycations and polyanions.
Keywords:
capillary isotachophoresis; polyelectrolytes; effective charge
Available at various institutes of the ASCR
Capillary isotachophoresis and zone electrophoresis applied to determination of effective charge of polyelectrolytes
Capillary electromigration methods, isotachophoresis (CITP) and zone electrophoresis (CZE) were applied to determination of effective charge of poly-alpha-L-glutamic acid and poly-alpha-L-lysine using ...
Determination of stability constants of [Gly6]-antamanide complexes with small cations by affinity capillary electrophoresis
Pangavhane, Sachin; Makrlík, E.; Ruzza, P.; Kašička, Václav
2016 - English
Affinity capillary electrophoresis (ACE) was employed for the determination of apparent stability constants Kst of complexes of cyclic peptide [Gly6]-antamanide ([Gly6]-AA) with alkali and alkali-earth metal ions: Li+, Na+, K+, Rb+, Cs+, NH4+, and Ca2+. Kst was determined from the dependence of effective mobility of [Gly6]-AA on the concentration of these ions in the background electrolyte using the non-linear regression analysis. Kst were found to be in the range 13.3 – 26.3.
Keywords:
affinity capillary electrophoresis; [Gly6]-antamanide; stability constant
Available at various institutes of the ASCR
Determination of stability constants of [Gly6]-antamanide complexes with small cations by affinity capillary electrophoresis
Affinity capillary electrophoresis (ACE) was employed for the determination of apparent stability constants Kst of complexes of cyclic peptide [Gly6]-antamanide ([Gly6]-AA) with alkali and ...
Investigation of acid-based properties of mono- and diaza[5]helicenes by non-aqueous capillary electrophoresis and quantum chemical calculations
Šolínová, Veronika; Štěpánová, Sille; Jančařík, Andrej; Klívar, Jiří; Šámal, Michal; Stará, Irena G.; Vacek Chocholoušová, Jana; Vacek, Jaroslav; Starý, Ivo; Kašička, Václav
2016 - English
Non-aqueous capillary electrophoresis (NACE) using methanol (MeOH) as a solvent of the background electrolytes was used to determine the thermodynamic acidity (ionization) constants (pKa) of a series of monoaza[5]helicenes and diaza[5]helicenes protonated to the first degree in MeOH and water. Depending on the number and position of the nitrogen atoms in their molecules, the analyzed aza[5]helicenes were found to be weak to moderate bases with methanolic pKa,MeOH in the range 3.90-8.75 and with aqueous pKa,H2O in the range 3.53-8.28.
Keywords:
capillary electrophoresis; azahelicenes; acidity constant
Available at various institutes of the ASCR
Investigation of acid-based properties of mono- and diaza[5]helicenes by non-aqueous capillary electrophoresis and quantum chemical calculations
Non-aqueous capillary electrophoresis (NACE) using methanol (MeOH) as a solvent of the background electrolytes was used to determine the thermodynamic acidity (ionization) constants (pKa) of a series ...
Capillary electrophoretic separation and structure-mobility relationship study of cyclic antimicrobial peptides
Tůmová, Tereza; Monincová, Lenka; Čeřovský, Václav; Kašička, Václav
2016 - English
Capillary electrophoresis (CE) has been employed for qualitative and quantitative analysis, separation and physicochemical characterization of antimicrobial peptides isolated from the venom of eusocial bee Lassioglossum laticeps. From the CE experiments at various pH, the important physico-chemical parameters of analyzed peptides, effective mobilities and acidity constants were determined and the structure-mobility relationships of peptides with variable intramolecular cyclization of their molecules were investigated.
Keywords:
antimicrobial peptides; capillary electrophoresis; structure-mobility relationships
Available at various institutes of the ASCR
Capillary electrophoretic separation and structure-mobility relationship study of cyclic antimicrobial peptides
Capillary electrophoresis (CE) has been employed for qualitative and quantitative analysis, separation and physicochemical characterization of antimicrobial peptides isolated from the venom of ...
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 ...
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 ...
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 ...
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, ...
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