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Evaluation of the 33 synthesized nitrophenol-based markers of isoelectic point
Duša, Filip ; Moravcová, Dana ; Šlais, Karel
33 nitrophenol-based compounds, which absorb at ultraviolet as well as visible wavelengths, were selected as candidates for marking isoelectric points (pI) over the pH range from 3 to 10. The evaluation and selection of the candidate structures included structure-based calculations of acid-base properties. The selected compounds were further tested experimentally using capillary isoelectric focusing. The experimental analysis excluded two compounds due to producing double peaks during the analysis. Overall, 31 novel compounds were identified as suitable pI markers.
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A Validatation of non-invasive method for diagnostic of cystic fibrosis based on ion ratios determined by CE-C4D
Ďurč, P. ; Lačná, J. ; Dosedělová, V. ; Foret, František ; Homoľa, L. ; Pokojová, E. ; Malá, M. ; Skřičková, J. ; Dastych, M. ; Vinohradská, H. ; Dřevínek, P. ; Skalická, V. ; Kubáň, Petr
A validation of novel approach for diagnosis of cystic fibrosis (CF) is presented. The method is very simple and fast, since for collection of samples, only wiping of the skin of forearm is needed. The collected sample is analyzed by capillary electrophoresis with contactless conductometric detection (CE-C4D). Ion ratios are determined as ratios of peak area of chloride anion and peak areas of selected cations. It is possible to distinguish between cystic fibrosis patients and healthy individuals when ion ratio is applied as diagnostic factor. In here, we present analytical parameters of developed method (limits of detection, limits of quantification, repeatability of migration times, repeatability of peak areas) and ROC curve, which reveals high sensitivity and specificity of the developed method.
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Impact of post-harvest processing, geographical locality and production year on quality of selected medicinal plants
Burdějová, Lenka ; Polovka, M. ; Pořízka, J.
This study deals with the assessment of the impact of post-harvest treatment, geographical location and production years on 32 selected characteristics of medicinal plants grown in the Czech Republic. Dimethyl sulfoxide herbal extracts characteristics were evaluated by spectroscopic and chromatographic techniques. The results were processed by analysis of variance and multivariate statistical tools. Obtained results clearly proved the successful differentiation of herbal samples by means of canonical discrimination analysis according to post-harvest treatment (100%), geographical origin (82.9%) and production year (96.1%) confirming that studied factors may have significant effect on quality of medicinal plants.
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Temperature-programed micro-HPLC analysis of fatty acid methyl esters with APCI-MS detection
Vrkoslav, Vladimír ; Rumlová, Barbora ; Cvačka, Josef
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.
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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
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.
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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
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.
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