Počet nalezených dokumentů: 402
Publikováno od do

Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers
Josypčuk, Bohdan; Barek, J.; Josypčuk, Oksana
2018 - anglický
A new type of tubular detector (TD+AuxE) was proposed, fabricated, tested and compared\nwith a typical silver amalgam tubular detector developed earlier. Non-stop-flow differential\npulse voltammetric anodic stripping method (AS-DPV) and amperometric method in a\nglucose oxidase biosensor arrangement were tested. Both detectors were applied for AS-DPV\nmeasurements in flow systems for the first time. The proposed combination of tubular\ndetector with auxiliary electrode provides a much greater current response than the classic\narrangement with three individual electrodes. All relevant parameters (potentials of\naccumulation or detection, flow rate, analyte concentrations, shielding sleeve length, etc.)\nwere optimized for the developed TD+AuxE. Klíčová slova: Flow analysis; Amperometry; Voltammetry Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers

A new type of tubular detector (TD+AuxE) was proposed, fabricated, tested and compared\nwith a typical silver amalgam tubular detector developed earlier. Non-stop-flow differential\npulse voltammetric ...

Josypčuk, Bohdan; Barek, J.; Josypčuk, Oksana
Ústav fyzikální chemie J. Heyrovského, 2018

Aplikace mikro-objemové voltametrické cely pro stanovení doxorubicinu hydrochloridu
Skalová, Štěpánka; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2018 - český
Byla úspěšně otestována aplikace mikro-objemové voltametrické cely na příkladu stanovení protinádorového léčiva doxorubicinu hydrochloridu. Objem analyzovaného vzorku činil 50 mikroL s LOD 0,39 micromol L-1 a LDR 0,4-10 mikromol L-1. Tato mikro-objemová cela byla také úspěšně použita k analýze tohoto analytu v modelových vzorcích pitné vody a lidské moči. Doxorubicin is an anticancer drug, which is used for treatment of various cancer types. It contains a quinone structure, similarly as some other drugs belonging to the same category (e.g., daunorubicin and epirubicin). Its monitoring can lead to optimization of individual patient dosages and increase chances for recovery of patients. A micro-volume voltammetric cell and differential pulse cathodic stripping voltammetry have been used for determination of doxorubicin hydrochloride. A volume of used sample was 50 microL. Limit of detection was 0.39 micromol L-1. An applicability of this method was verified on samples of drinking water and of human urine. Klíčová slova: Doxorubicine hydrochloride; Voltametry; Micro-volume Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Aplikace mikro-objemové voltametrické cely pro stanovení doxorubicinu hydrochloridu

Byla úspěšně otestována aplikace mikro-objemové voltametrické cely na příkladu stanovení protinádorového léčiva doxorubicinu hydrochloridu. Objem analyzovaného vzorku činil 50 mikroL s LOD 0,39 ...

Skalová, Štěpánka; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2018

Chování metalothieneinů a fytochelatinů na rtuťových a amalgámových elektrodách
Šestáková, Ivana; Navrátil, Tomáš; Josypčuk, Bohdan
2018 - český
Při použití elektrod AgSAE či CuSAE pro elektrochemická měření s metalothioneiny či fytochelatiny vznikají příslušné Ag-MT, Cu-MT, Ag-PC či Cu-PC komplexy. V čistých elektrolytech a pro nízké koncentrace analytů jsou odezvy lineárně závislé na jejich koncentraci, odezvu je možné zvýšit akumulací při vhodném potenciálu. Pro reálné vzorky je podstatný negativní vliv matrice, který může vést až k nutnosti přípravy nového povrchu a jeho aktivace pro každý jednotlivý záznam. The presence of cysteine residues in molecules of metallothioneins or phytochelatins is crucial for their electrochemical behavior. At mercury electrodes, the reduction of\ntetracoordinated Cd and Zn in molecule of mamamalian MT is observed in solution of pH 8- 8.5, whereas with lowering pH or at presence of excessive ions, signals of differently coordinated or free metal ions appear. Such changes were confirmed on model complexes with phytochelatin PC2 .Using amalgam electrodes CuSAE or AgSAE for voltammetry of metallothioneins or phytochelatins, their Cu or Ag complexes are formed on the electrode surface, which could be with limitations - employed for the analytical purposes. Klíčová slova: metallothioneins; amalgam electrode; voltammetry Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Chování metalothieneinů a fytochelatinů na rtuťových a amalgámových elektrodách

Při použití elektrod AgSAE či CuSAE pro elektrochemická měření s metalothioneiny či fytochelatiny vznikají příslušné Ag-MT, Cu-MT, Ag-PC či Cu-PC komplexy. V čistých elektrolytech a pro nízké ...

Šestáková, Ivana; Navrátil, Tomáš; Josypčuk, Bohdan
Ústav fyzikální chemie J. Heyrovského, 2018

Determination of Roughness Factor and Fractal Dimension of Zirconium in its Native and Surface Modified State using Atomic Force Microscopy. Effect of the Hydrogen\nEvolution Reaction on the Surface Structure
Novák, M.; Kocábová, Jana; Kolivoška, Viliam; Pospíšil, Lubomír; Macák, J.; Cichoň, Stanislav; Cháb, Vladimír; Hromadová, Magdaléna
2018 - anglický
Atomic force microscopy (AFM) was used to characterize surface morphology of pristine zirconium, Si modified and FeSi modified zirconium electrodes prior and after hydrogen evolution at potentials negative of the open circuit potential value. Two main characteristic parameters were obtained from the ex situ AFM height images, namely, the roughness factor and fractal dimension of the studied surface. The effect of hydrogen evolution reaction on the electrode surface morphology was discussed. Fractal dimension values were used successfully to explain the non ideality of the interfacial capacitance. Klíčová slova: zirconium electrode; atomic force microscopy; fractal dimension Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Determination of Roughness Factor and Fractal Dimension of Zirconium in its Native and Surface Modified State using Atomic Force Microscopy. Effect of the Hydrogen\nEvolution Reaction on the Surface Structure

Atomic force microscopy (AFM) was used to characterize surface morphology of pristine zirconium, Si modified and FeSi modified zirconium electrodes prior and after hydrogen evolution at potentials ...

Novák, M.; Kocábová, Jana; Kolivoška, Viliam; Pospíšil, Lubomír; Macák, J.; Cichoň, Stanislav; Cháb, Vladimír; Hromadová, Magdaléna
Ústav fyzikální chemie J. Heyrovského, 2018

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
2018 - anglický
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. Klíčová slova: oxidation; flavonoids; decomposition Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Differences in Oxidation Mechanism of Selected Bioflavonoids, UV-Vis and IR Spectroelectrochemical Study

The oxidation of selected bioflavonoids (quercetin, rhamnazin, fisetin, rhamnetin, taxifolin, luteolin, silybin and 2,3-dehydrosilybin) was studied by electrochemical and spectroscopic methods. The ...

Sokolová, Romana; Fiedler, Jan; Ramešová, Šárka; Kocábová, Jana; Degano, I.; Quinto, A.; Křen, Vladimír
Ústav fyzikální chemie J. Heyrovského, 2018

Redox Properties of Fluorinated Derivatives of 1,3-Diphenylisobenzofuran Chromophores for Singlet Fission
Šimková, Ludmila; Ludvík, Jiří
2018 - anglický
Derivatives of 1,3-diphenylisobenzofuran attract interest because they should be efficient as the molecules for singlet fission. The understanding of singlet fission in isolated molecules might be advantageous for use as solar cell sensitizers. This study is focused on fluorinated derivatives of 1,3-diphenylisobenzofuran and the effect of the position of fluorine atoms on their redox properties. For characterization of the redox properties standard electrochemical methods, and in situ UV-vis and EPR spectroscopy techniques were used. Klíčová slova: 1,3-diphenylisobenzofuran; fluorinated derivatives; spectroelectrochemistry Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Redox Properties of Fluorinated Derivatives of 1,3-Diphenylisobenzofuran Chromophores for Singlet Fission

Derivatives of 1,3-diphenylisobenzofuran attract interest because they should be efficient as the molecules for singlet fission. The understanding of singlet fission in isolated molecules might be ...

Šimková, Ludmila; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2018

Electrochemical Monitoring of the Water Clusters Formation in an Organic Solvent in the Presence of Hydrated Ions
Mareček, Vladimír
2018 - anglický
An electrochemical method has been developed that makes it possible to monitor the\ndynamics of the co-extraction of water with hydrated chloride ions at the interface between\ntwo immiscible electrolyte solutions (ITIES). The interfacial potential was controlled by the\ndistribution of a common tetralkylammonium (TAA+) ion. Changes in the TAA+\nconcentration at the interface were monitored by measuring the open circuit potential (OCP).\nTransfer of hydrated chloride ions is accompanied by the transfer of TAA+, decreasing its\nconcentration on the aqueous side of the interface. This process involves the co-extraction of\nwater molecules with the hydrated chloride ions and the formation of water clusters in the\norganic solvent phase. The ability to monitor the process from the very beginning of interface\nformation allowed us to obtain important kinetic data. Klíčová slova: Liquid/liquid interface; Water co-extraction dynamics; Emulsification Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Monitoring of the Water Clusters Formation in an Organic Solvent in the Presence of Hydrated Ions

An electrochemical method has been developed that makes it possible to monitor the\ndynamics of the co-extraction of water with hydrated chloride ions at the interface between\ntwo immiscible ...

Mareček, Vladimír
Ústav fyzikální chemie J. Heyrovského, 2018

Silver Solid Amalgam Electrodes as Perspective Tools for Sensitive Voltammetric Determinations of Food Azo Dyes Amaranth and Allura Red AC
Tvorynska, S.; Barek, J.; Josypčuk, Bohdan
2018 - anglický
In this paper, for the first time, the electrochemical behaviours of the food azo dyes Amaranth (E 123) and Allura Red AC (E 129) were investigated on two modifications of silver solid amalgam electrode, namely mercury meniscus modified, polished and compared with hanging mercury drop electrode using differential pulse voltammetry and direct current voltammetry. The effect of adsorption and the reduction mechanism on tested electrodes were described in detail. Measurements with amalgam electrodes showed good reproducibility, stability and high sensitivity. As a result, they were successfully applied for the determination of investigated azo dyes in different commercial drink samples. Klíčová slova: voltammetry; azo dyes; amaranth Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Silver Solid Amalgam Electrodes as Perspective Tools for Sensitive Voltammetric Determinations of Food Azo Dyes Amaranth and Allura Red AC

In this paper, for the first time, the electrochemical behaviours of the food azo dyes Amaranth (E 123) and Allura Red AC (E 129) were investigated on two modifications of silver solid amalgam ...

Tvorynska, S.; Barek, J.; Josypčuk, Bohdan
Ústav fyzikální chemie J. Heyrovského, 2018

Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors
Koláčná, Lucie; Tobrman, T.; Ludvík, Jiří
2018 - anglický
A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core were electrochemically investigated in order to determine the influence of individual parts of the molecule on the redox properties, to describe the location of the reduction center and to understand the structure - redox activity relationship of the mentioned compounds. Klíčová slova: pyrene; cyclobutene; polarography Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors

A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core ...

Koláčná, Lucie; Tobrman, T.; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2018

Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš
2018 - anglický
Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being developed. Wide variety of water-immiscible supported liquid membranes\n(SLMs) were tested. Highest enrichment factors were obtained using butyl benzoate as SLM.\nEnrichment factors for 30 min HF-LPME were 3. 0.74 for HVA and 5. 0.45 for VMA,\nrespectively. Repeatability of HF-LPME of microM HVA or VMA was 19.0% for HVA and\n7.9 % for VMA (n=5), respectively. Klíčová slova: Hollow-fibres; Liquid phase microextraction; Voltammetry Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers

Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being ...

Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš
Ústav fyzikální chemie J. Heyrovského, 2018

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