National Repository of Grey Literature 30 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Oxidation and Reduction of Selected 1,10-Phenantrolines
Wantulok, J. ; Sokolová, Romana ; Nycz, J. E. ; Degano, I.
Derivatives of 1,10-phenanthroline (Phen) are well-known bident ligands which had a lot of interesting applications thanks to their coordination abilities. Selected 1,10-phenanthroline compounds were studied by electrochemical methods. Depending on their different substituents were observed several oxidation and reduction voltammetric peaks. The study involves also in situ spectroeletrochemistry, infrared spectroscopy and identification of products by HPLC-DAD and HPLC-ESI MS/MS.
On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside
Castano, A. ; Sokolová, Romana ; Degano, I.
The UV-Vis spectroelectrochemical cell containing an optically transparent platinum net used as the working electrode was tested in two regimes of electrochemical measurement, cyclic voltammetry and chronoamperometry, respectively. A three electrode setup used silver quasi reference electrode and platinum electrode serving as a counter electrode. The calibration of the spectroelectrochemical cell was performed for one-electron oxidation processes as well as for two-electron oxidations. The spectral changes during the oxidation of luteolin-7-O-Glucoside gave the information about the electroactive chromophores in molecule. Resulted spectra were compared with luteolin. The identification of products of oxidation was done by complementary analytical techniques HPLC-DAD and HPLC-ESI-MS/MS.
Differences in Oxidation Mechanism of Selected Bioflavonoids, UV-Vis and IR Spectroelectrochemical Study
Sokolová, Romana ; Fiedler, Jan ; Ramešová, Šárka ; Kocábová, Jana ; Degano, I. ; Quinto, A. ; Křen, Vladimír
The oxidation of selected bioflavonoids (quercetin, rhamnazin, fisetin, rhamnetin, taxifolin, luteolin, silybin and 2,3-dehydrosilybin) was studied by electrochemical and spectroscopic methods. The oxidation mechanism and formation of oxidation products depends on the chemical structure. Only small differences in the chemical structure of compounds with flavone, flavanone and flavonol motif result in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESIMS/MS and HPLC-DAD.
Study of Metabolism of Synthetic Cannabinoids. Electrochemical Properties of JWH-018
Obluková, Michaela ; Sokolová, Romana ; Čabala, R.
In the recent years, many new substances have appeared in the drug market, which are abused for their psychoactive effect. They serve as alternative to classical drugs (heroin, cocaine, ecstasy) due to their legal status. The great concern is the ineffectiveness of the current methods of toxicological screening of biological samples to identify these new compounds. It is essential to know the metabolism pathway of these psychoactive substances for a development of a new efficient method for their detection. This report is devoted to understanding of oxidation and reduction mechanism of JWH-018 and JWH-250 by means of cyclic voltammetry and to identification of their redox products.
Study of electrochemical behaviour of cinchona alkaloids at boron doped diamond electrode
Brunovská, Veronika ; Schwarzová, Karolina (advisor) ; Sokolová, Romana (referee)
The anodically oxidized boron doped diamond electrode was used in this study to investigate the electrochemical behaviour of quinoline and its derivative quinine in the anodic area in the aqueous medium, namely using methods of cyclic voltammetry (CV), square wave voltammetry (SWV) and square wave adsorptive stripping voltammetry (SWAdSV) and to adress their potential in voltammetric analysis. It was found by means of SWV that quinoline exhibits one anodic signal in BR buffer in the range of pH 3.0 - 12.0. Quinine shows one anodic signal in the range pH 2.0 - 5.0 later; at higher pH values other 2 to 4 less distinctive signals are formed, i.e, the mechanism is influenced by the presence of quinuclide ring and functional groups at the quinoline skeleton of quinine. It was proved by cyclic voltammetry that the anodic electrode reaction of quinoline is controlled by diffusion; for quinine the results are rather ambiguous. Using the optimized parameteres of SWV (Estep = 5 mV; f = 40 Hz and A = 50 mV) and media of BR buffer pH 5,0, linear dependence peaks height of quinoline on its concentration in the range of 1∙10-7 to 1∙10-4 mol.l-1 was obtained with limit of detection 3.53∙10-7 mol.l-1 . The concetration dependence of quinine under the same conditions is not linear in the range of 6∙10-7 to 1∙10-4...
Supported Phospholipid Bilayer at the Conductive Interface
Sokolová, Romana ; Kocábová, Jana ; Kolivoška, Viliam ; Gál, M.
The interactions of ethanol and flavonoid compounds with supported phospholipid bilayer\nwere studied by means of electrochemical methods and scanning probe techniques. The\nstability of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) phospholipid bilayer\nsupported on different types of conductive substrate was investigated. The relationship\nbetween the method of lipid deposition and the formation of several types of lipid structures\nincluding vesicles, hemimicelles, patches and single bilayers on the interface is discussed.
Phospholipid Modified Glassy Carbon Electrode and its Application for Determination of Pesticides
Švecová, H. ; Sokolová, Romana ; Součková, J. ; Skopalová, J. ; Barták, P.
In this article we described glassy carbon electrode modified with Asolectin (mixture of phosholipids). Properties of phospholipid layer, such as its thickness or solidity, were investigated using atomic force microscopy (AFM). The modified electrode was applied for square wave voltammetry (SWV) measurements to study interactions of pesticide paraquat with phospholipid layer and to detect paraquat selectively in real samples of river water.
Voltammetric Behavior of Explosive Potassium Salt of 2,4-Dinitrobenzofuroxan\non Electrodes with Mercury Surface
Šelešovská, R. ; Sokolová, Romana ; Matyáš, R. ; Janíková, L.
Voltammetric behavior of potassium salt of 2,4-dinitrobenzofuroxan (KDNBF) has been\nfirstly studied using hanging mercury drop electrode (HMDE) and silver solid amalgam\nelectrode (AgSAE). Cyclic voltammetry was applied for the measurements of dependences on\npH and scan rate required for the elucidation of the ongoing electrode reactions and\ndifferential pulse voltammetry served for the development of sensitive method for KDNBF\ndetermination.
Oxidation of Bioflavonoids in Respect to their Chemical Structure
Sokolová, Romana ; Ramešová, Šárka ; Kocábová, Jana ; Degano, I.
The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of bioflavonoids resulted in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESI-MS/MS and HPLC-DAD.
Oxidation Mechanism of Rhamnetin, a Bioflavonoid Compound
Ramešová, Šárka ; Sokolová, Romana ; Degano, I.
The natural flavonoid rhamnetin (2-(3,4-dihydroxyfenyl)-3,5-dihydroxy-7-methoxychromen-4-one) is important bioactive compound. Rhamnetin was studied in aqueous solution by electrochemical methods. The oxidation mechanism proceeds in sequential steps, which correspond to the hydroxyl oxidation of groups in the three aromatic rings. The study is based on in situ spectroelectrochemistry and identification of products by HPLC-DAD and HPLC–ESI MS/MS.

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