Ústav fyzikální chemie J. Heyrovského

Nejnovější přírůstky:
2017-10-30
13:46
Miniaturized Boron Doped Diamond Film Electrode for Neuroblastoma Biomarkers Determination
Hrdlička, Vojtěch ; Barek, J. ; Navrátil, Tomáš ; Taylor, Andrew
Cathodically pretreated miniaturized boron doped diamond film\nelectrode was successfully tested for the purposes of in-situ determination\nof neuroblastoma biomarkers after hollow-fibre based\nmicroextraction. Electrode was tested using K3[Fe(CN)6] and vanillylmandelic\nacid as model substances . Limits of detection and\ndetermination are 2.2 and 6.6 mu mol L-1, respectively. Linear range was\n2.2-100 mu mol L-1, repeatability 1.34% (n = 10).

Úplný záznam
2017-10-30
13:46
Voltammetric Determination of Tumor Biomarkers using Flow Injection Analysis with Amperometric Detection
Makrlíková, Anna ; Matysik, F.-M. ; Barek, J. ; Vyskočil, V.
Three tumor biomarkers (homovanillic acid, vanillylmandelic acid,\nand 5-hydroxyindole-3-acetic acid) have been determined by flow\ninjection analysis with amperometric detection at screen-printed\ncarbon electrodes in optimum medium of Britton-Robinson buffer\n(0.04 mol l-1, pH = 2.0). Dependences of the peaks current on the\nconcentration of biomarkers were linear in the tested concentration\nregion from 0.05 to 100 mu mol l-1, with the limits of detection of\n0.065 mu mol l-1 for homovanillic acid, 0.053 mu mol l-1 for vanillylmandelic\nacid, and 0.033 mu mol l-1 for 5-hydroxyindole-3-acetic acid (calculated\nfrom heights), and 0.024 mu mol 1-1 for homovanillic acid,\n0.020 mu mol l-1 forvanillylmandelic acid, and 0.012 mu mol l-1 for 5-hydroxyindole-3-acetic acid (calculated from areas), respectively.

Úplný záznam
2017-10-30
13:46
Pilot Experiments With a Micro-Volume Voltammetric Cell for the Determination of Electrochemically Reducible Organic Compounds
Skalová, Štěpánka ; Barek, J. ; Rodrigues, J. A. ; Goncalves, L.M. ; Navrátil, Tomáš ; Vyskočil, V.
A new micro-volume voltammetric cell for analysis of small volumes\nof electrochemically reducible organic compounds was developed\nand tested. The sample (20-100 mu L) is placed in a narrow glass tube\nwith an agar membrane at the bottom and the working electrode is\nimmersed into the sample. The agar membrane, as anion permeable\nlayer, electrically connects the workin g e lectrode immersed in the\nanalysed sample in the glass tube with a large-volume compartment\n(20 mL) filled with Britton-Robinson buffer, where conventional nonminiaturized\nreference and auxiliary electrodes are placed. The system\nwas tested using a polished silver solid amalgam electrode\n(p-AgSAE) as a working electrode. Sodium anthraquinone-2-sulfonate\nwas used as a model compound because it is intended to use this\nsystem to monitor electrochemically reducible organic compounds.

Úplný záznam
2017-06-12
14:36
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Hromadová, Magdaléna ; Kocábová, Jana ; Kolivoška, Viliam ; Pospíšil, Lubomír
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results show that the oxide growth kinetics depends on pH of the electrolyte\nsolution and the total amount of irreversibly formed oxide under the potentiodynamic\nconditions decreases with decreasing buffer pH in accord with thermodynamic considerations.\nCathodic current corresponding to hydrogen evolution reaction diminishes in the presence of\nanodically modified electrode compared to bare zirconium.

Úplný záznam
2017-06-12
14:36
Graphite Electrode Modified by Poly(Methylene Blue) and its Electrocatalytic Activity towards Hydrogen Sulfide Oxidation
Zlámalová, Magda ; Janda, Pavel ; Nesměrák, K.
This research is focused on the electrochemical synthesis and characterization of\npoly(methylene blue) (pMB). Two different carbon-based electrode substrates, basal plane\nhighly oriented pyrolytic graphite (HOPG) and pencil graphite electrode (PGE), have been\nmodified by conductive film of pMB. Electrochemical properties and nanomorphological\nchanges have been investigated by cyclic voltammetry and atomic force microscopy.\nImproved electroactivity of the modified electrodes (PGE/pMB and HOPG/pMB) towards\nsulfhydryl group has been observed and examined modified electrodes were researched for\ntheir possible application in electrochemical sensor for hydrogen sulfide in aqueous solutions.

Úplný záznam
2017-06-12
14:36
Electrochemical biosensors with flow-through enzymatic reactors
Josypčuk, Oksana ; Josypčuk, Bohdan
Twelve enzymatic biosensors with various silica powder reactors were fabricated and tested.\nExperiments with six silica materials showed that mesoporous silica SBA-15 was the best one\nin terms of covering by enzymes, sensitivity and lifetime of biosensors. The current response\nof the SBA15-glucose oxidase (GOx) sensor started to decrease only after 200-day testing.\nThe used amalgam tubular detector in a flow system allowed working at highly negative\npotentials. Statistical results of parallel measurements of model solutions with the fabricated\nbiosensors show their high accuracy and sensitivity. The proposed SBA15-GOx biosensor\nwas used for determination of glucose in commercial honey.

Úplný záznam
2017-06-12
14:36
Charge Transport through Molecular Towers Based on Tetraphenylmethane Tripods
Kolivoška, Viliam ; Šebera, Jakub ; Lindner, M. ; Valášek, M. ; Mayor, M. ; Mészáros, G. ; Gasior, Jindřich ; Hromadová, Magdaléna
Molecular platforms with multiple anchors were introduced recently to provide robust\ncoupling between molecular electronic components and metallic electrodes. In this work,\ncharge transport in tower-shaped single molecule conductors based on tetraphenylmethane\ntripod possessing three thiol anchors is investigated by scanning tunneling microscopy break\njunction technique. The effect of tripod substitution pattern and number of repeating units in\nmolecule is addressed. The substitution was found to influence conductance value in early\nstages of molecular junction evolution, where tower lays parallel to surface. In late stages, the\ncharge is transported through principal molecular axis and junction breaks thermally in tilted\nconfiguration.

Úplný záznam
2017-06-12
14:36
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.

Úplný záznam
2017-06-12
14:36
Single Molecule Conductance and Junction Formation in Solution. Solvent Effect
Lachmanová, Štěpánka ; Šebera, Jakub ; Gasior, Jindřich ; Dupeyre, G. ; Lainé, P. P. ; Mészáros, G. ; Hromadová, Magdaléna
The single molecule conductance of expanded pyridinium derivative terminated by pyridyl\nnitrogen as an anchoring group at both ends of the molecule in two different environments\nwas measured by scanning tunneling microscopy break junction technique (STM-BJ). The\nvalues obtained in commonly used 1,3,5-trimethylbenzene (TMB) significantly differ from\nthe values acquired in a mixture of TMB and ethanol. Markedly lower junction length and\nhigher conductance indicate strong influence of adsorption of the molecule to the substrate\nsurface in pure TMB compared to the TMB and ethanol mixture.

Úplný záznam
2017-06-12
14:36
Determination of 5-hydroxyindole-3-acetic acid using Flow Injection Analysis with Electrochemical Detection
Makrlíková, Anna ; Matysik, F.-M. ; Navrátil, Tomáš ; Barek, J. ; Vyskočil, V.
Tumour biomarker, 5-hydroxyindole-3-acetic acid, has been determined at screen-printed carbon electrodes using flow injection analysis with amperometric detection. Britton-Robinson buffer (0.04 mol-l-1 , pH 2.0) was used as an optimum carrier solution.\nDependence of the peak current on the analyte concentration was linear in the whole tested\nconcentration range (from 0.5 to 100 mikromol-l-1) with limits of detection 0.033 mikromol-l-1 \n(calculated from peak heighst) and 0.012 mikromol-l-1 (calculated from peak areas).

Úplný záznam