No (405)
Yes (4)
Used filters
(3)
Number of found documents:
409
Published from
to
Tebuconazole and its behaviour in the presence of magnesium
Jakl, M.; Jaklová Dytrtová, Jana
2020 - English
Tebuconazole is a fungicide frequently used in agriculture. Its possible impact to (non-)target species is influenced by its presence. Moreover, the presence of triazoles in soil has an impact to bioavailability of nutrients. This study brings the information potentially useful in the evaluation of tebuconazole fate in the environment. The studies based on the electrospray gas phase experiments provide an estimation of the tebuconazole ability to create complexes with magnesium.
Keywords:
triazoles; Mg(II); mass spectrometry; ESI-MS; complexes
Available at various institutes of the ASCR
Tebuconazole and its behaviour in the presence of magnesium
Tebuconazole is a fungicide frequently used in agriculture. Its possible impact to (non-)target species is influenced by its presence. Moreover, the presence of triazoles in soil has an impact to ...
Structural characterization of fatty acids with triple bond and unusual double bond positions by HPLC/APCI-MS2
Horká, Petra; Vrkoslav, Vladimír; Cvačka, Josef
2019 - English
Fatty acid methyl esters (FAMEs) were analyzed by reversed-phase HPLC coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry. Acetonitrile was used as mobile phase. The gas-phase reactions of acetonitrile and unsaturated FAMEs in the APCI source provided [M + C3H5N]+• adducts. Subsequent MS/MS analysis of these ions gave diagnostic fragments. The formation and fragmentation of the acetonitrile-related adducts were utilized for the structural characterization of FAME with isolated double bonds in (Z)-9,19-hexacosadienoic acid methyl ester, FAME with conjugated double bonds in (Z)-9,11-octadecadienoic acid methyl ester and FAME with a triple bond in 9-octadecynoic acid methyl ester.
Keywords:
acetonitrile-related adducts; acetylenic lipids; multiple bond localization; mass spectrometry
Available at various institutes of the ASCR
Structural characterization of fatty acids with triple bond and unusual double bond positions by HPLC/APCI-MS2
Fatty acid methyl esters (FAMEs) were analyzed by reversed-phase HPLC coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry. Acetonitrile was used as mobile phase. The gas-phase ...
Method optimization for simultaneous separation of six triazole fungicides in HPLC
Kovač, Ishak; Martín Miján, P.; Del Sol Vega Alegre, M.; Dejmková, H.; Jaklová Dytrtová, Jana; Schwarzová, K.
2019 - English
Triazole pesticides are widely used in agriculture against fungi pathogens. Their application is not restricted on just one member of the group, more importantly, the application is usually carried out in the mixture of two or more triazoles. Hence, this work focuses on simultaneous separation and detection of six triazole fungicides: penconazole, tebuconazole, propiconazole, cyproconazole, fenbuconazole, and difenoconazole. Two different columns were tested with different parameters for isocratic and gradient elution in HPLC with UV detector. On Purospher Reverse Phase-18 column with gradient elution isomers of triazoles cyproconazole and propiconazole were successfully separated. However, on this column, there was an overlap of some triazoles. In contrast, the isocratic elution on Kromasil Eternity-5-PhenylHexyl column showed sufficient separation capabilities. In further research, chiral separation of triazoles will be considered using capillary electrophoresis.
Keywords:
capillary electrophoresis; HPLC; triazole pesticides
Available at various institutes of the ASCR
Method optimization for simultaneous separation of six triazole fungicides in HPLC
Triazole pesticides are widely used in agriculture against fungi pathogens. Their application is not restricted on just one member of the group, more importantly, the application is usually carried ...
Aldrithiol-2 as a new derivatization agent for double bond localization in unsaturated compounds by mass spectrometry
Strmeň, Timotej; Cvačka, Josef
2019 - English
A new method for localizing double bonds in lipids using derivatization with 2,2'-clipyridyl disulfide (Aldrithio-2) and electrospray ionization mass spectrometry (EST-MS) is presented. The derivatization introduces a permanent charge to the molecules. When collisionally activated, the derivatives provide diagnostic peaks useful for establishing the position of the original double bond. Since permanent charge of the derivative significantly increases the detectability of analytes, the method works well also for of very low polarity like hydrocarbons.
Keywords:
aldrithiol-2; double bond; electrospray; lipids; mass spectrometry
Available at various institutes of the ASCR
Aldrithiol-2 as a new derivatization agent for double bond localization in unsaturated compounds by mass spectrometry
A new method for localizing double bonds in lipids using derivatization with 2,2'-clipyridyl disulfide (Aldrithio-2) and electrospray ionization mass spectrometry (EST-MS) is presented. The ...
Monitoring of enzymatic enantioselective acetylation of gem-difluorinated alcohols by capillary electrophoresis
Šolínová, Veronika; Pomeisl, Karel; Lamatová, Nikola; Pohl, Radek; Brabcová, Jana; Krečmerová, Marcela; Kašička, Václav
2018 - English
A new fast and highly efficient capillary electrophoretic (CE) method has been developed for chiral analysis of non-charged gem-difluorinated alcohol (3-(benzyloxy)-1,1-difluoro-propan-2-ol) using sulfobutylether-β-CD as chiral selector. The method was applied for monitoring of enzymatic (lipase mediated) enantioselective acetylation of the above alcohol and for determination of enantiomeric purity of both substrates and products of the enzymatic reaction.
Keywords:
enantioselective acetylation; difluorinated alcohols; capillary electrophoresis
Available at various institutes of the ASCR
Monitoring of enzymatic enantioselective acetylation of gem-difluorinated alcohols by capillary electrophoresis
A new fast and highly efficient capillary electrophoretic (CE) method has been developed for chiral analysis of non-charged gem-difluorinated alcohol (3-(benzyloxy)-1,1-difluoro-propan-2-ol) using ...
Affinity capillary electrophoresis applied to chiral separations of diquats and to determination of the stability constants of their complexes with sulfated cyclodextrins
Kašička, Václav; Bílek, Jan; Koval, Dušan; Sázelová, Petra; Talele, Harish Ramesh; Severa, Lukáš; Reyes Gutierrez, Paul Eduardo; Teplý, Filip
2018 - English
Affinity capillary electrophoresis (ACE) using an aqueous 22/35 mM sodium/phosphate buffer, pH 2.5, as the background electrolyte (BGE), and 6 mM randomly highly sulfated alpha-, beta- and gamma-cyclodextrins (CDs) as chiral selectors has been successfully applied for separation of (P)- and (M)-enantiomers of a series of eleven new diquats (DQs) and for estimation of the strength of their complexes with the above CDs. The apparent stability constants of the DQs-CDs complexes were determined from the simultaneous ACE measurements of the dependence of effective electrophoretic mobilities of (P)- and (M)-enantiomers of DQs on the concentrations of CDs in the BGE by nonlinear regression analysis. The DQs enantiomers formed strong complexes with all three types of CDs with the apparent stability constants in the range (7.80 547.4) × 103 L/mol.
Keywords:
affinity capillary electrophoresis; chiral separations; diquats
Available at various institutes of the ASCR
Affinity capillary electrophoresis applied to chiral separations of diquats and to determination of the stability constants of their complexes with sulfated cyclodextrins
Affinity capillary electrophoresis (ACE) using an aqueous 22/35 mM sodium/phosphate buffer, pH 2.5, as the background electrolyte (BGE), and 6 mM randomly highly sulfated alpha-, beta- and ...
Determination of stability constants of antamanide complexes with sodium and potassium ions by affinity capillary electrophoresis
Pangavhane, Sachin; Böhm, S.; Makrlík, E.; Ruzza, P.; Kašička, Václav
2018 - English
Affinity capillary electrophoresis (ACE) was applied for quantitative investigation of the interactions between important biomolecule, cyclic decapeptide antamanide (AA), cycl[-Val(1)-Pro(2)-Pro(3)-Ala(4)-Phe(5)-Phe(6)-Pro(7)-Pro(8)-Phe(9)-Phe(10)-], and sodium and potassium cations in methanol. Apparent stability constants of AA complexes with these alkali metal ions were determined from the dependence of effective mobility of AA on the concentration of these ions in the background electrolyte by the non-linear regression analysis. The AA complexes with Na+ and K+ ions were found to be relatively weak, with the apparent stability constants 343 L/mol and 35 L/mol, respectively.
Keywords:
affinity capillary electrophoresis; antamanide; binding constant
Available at various institutes of the ASCR
Determination of stability constants of antamanide complexes with sodium and potassium ions by affinity capillary electrophoresis
Affinity capillary electrophoresis (ACE) was applied for quantitative investigation of the interactions between important biomolecule, cyclic decapeptide antamanide (AA), ...
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 ...
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 ...
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 ...
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
Other bases