National Repository of Grey Literature 28 records found  previous11 - 20next  jump to record: Search took 0.02 seconds. 
Methanol Outbreak in the Czech Republic in the year 2012 – Almost Two Years Later
Navrátil, Tomáš ; Zakharov, S. ; Pelclová, D. ; Mrázová, K.
Almost two years ago, in autumn 2012, a large methanol outbreak was registered in the Czech Republic (CR). The first case was registered in September 2012 in Moravian city Havířov. The source was connected with illegal production and sale of adulterated spirits. About 50 dead and more than 150 cases of methanol intoxications have been reported since September 2012. Some cases of intoxications, connected with old methanol sources distributed in 2012, have been registered up to now. Not all of total amount of prepared methanolic drinks has been found and hundreds liters of toxic methanol have remained in stores or in households. n the other hand, many people intoxicated during this outbreak and classified as “fully recovered” by their hospital discharge, have suffered by sequels of their intoxication at present (visual and nervous system disturbances) and their number has been increasing.
Electrochemical Biosensors Based on Enzymatic Reactor with Amalgam Powder
Josypčuk, Bohdan ; Barek, J. ; Josypčuk, Oksana
Enzymatic reactor based on the powder of silver solid amalgam was suggested as the main part of biosensors in flow systems for the first time. 4-aminothiophenol, glutaraldehyde and enzyme were gradually bonded to the amalgam surface. Large surface of the fine amalgam particles maintains a big quantity of enzyme molecules. Biosensors were tested with enzymes ascorbate oxidase, glucose oxidase, catalase, tyrosinase and laccase. Electrochemical detection of the oxygen concentration change (for the first 3 enzymes) or the quinones concentration (tyrosinase and laccase) in the measured solution was done amperometrically by means of the tubular detector of silver solid amalgam. The current response of each biosensor was optimized with respect to the detection potential, the flow rate of the mobile phase, the injection volume and the enzymatic reactor volume. Under the found optimum conditions, concentration dependence and some statistical parameters of repeated measurements (relative standard deviation (RSD) for the studied enzymes was in the range 0.81 – 2.1 %) were measured. Biosensor with the ascorbate oxidase reactor was used for determination of ascorbic acid in the vitamin tablet Celaskon®. Results of the analysis were in good agreement with the contents of ascorbic acid declared by manufacturer and the RSD of these analyses was 2.0 %.
Detection of Thiram Pesticide using Copper Affinity Electrochemical Separation Electrospray Ionization Mass Spectrometry
Jaklová Dytrtová, Jana ; Navrátil, Tomáš ; Jakl, M. ; Nováková, Kateřina
The detection of pesticides in environmental matrices has a purpose in analytical chemistry and it is important for understanding their role in the environment 1-3. Direct detection of pesticides in environmental matrices is complicated due to many occurring interactions with metals (e.g., Ca, Cu, Mg, Zn). The experimental utilization of combining electrochemical cell with mass spectrometry is shown in the case of thiram (T). The method is based on high affinity of copper cations to many ligands.
The Influence of Labile Complexes on Cadmium Transport across Artificial Phospholipid Membrane
Šestáková, Ivana ; Parisová, Martina ; Nováková, Kateřina ; Navrátil, Tomáš
The influence of labile cadmium complexes on transport across phospholipid membrane with A23817 ionophore – the increase of the amount of transported cadmium ions - has been found when only diffusion controlled transport was applied. Lability of Cd-MA complex was demonstrated with stripping chronopotentiometry. Used experimental setup can be utilized for specifying conditions for transport of metal complexes with different stability.
Characterization of Liposomes Used as Model System of Biological Membranes by Glassy Carbon Electrode
Parisová, Martina ; Navrátil, Tomáš ; Šestáková, Ivana ; Barek, J.
This contribution deals with study and characterization of liposomes. These vesicles may serve as model membranes used for study of transporting processes of heavy metal ions across the real phospholipid membranes (PLMs). 1,2-dioleoyl-sn-glycero-3-phosphocholine was used for the formation of large unilamellar vesicles (LUV). These vesicles were prepared by hydration method. Interactions of cadmium ions with LUV in solution have been characterized using voltammetry, where glassy carbon electrode was used as the working electrode. Size and presence of liposomes in sample was proved by dynamic light scattering and free cadmium ions in samples were determined by differential pulse voltammetry.
Short Information on Methanol Outbreak in the Czech Republic in the year 2012
Navrátil, Tomáš ; Zakharov, S. ; Pelclová, D. ; Mrázová, K.
This contribution reports briefly on the large methanol outbreak in the Czech Republic (CR) in autumn 2012. The first case was registered in September 2012 in Havířov. The source was unknown at that time, but it was connected with the illegal production and sale of adulterated spirits. More than 130 cases of methanol intoxication have been reported during September 2012 – April 2013. 44 people died, about 1/5 of intoxicated patients have suffered by sequels of intoxication and their number have been increasing. Moreover, the samples of methanol can be found in some illegal stores and in some households up to now.
Characterization of Electrochemical Behavior of Lecithin-Cholesterol Mixture in Formation of Model Phospholipid Membranes
Nováková, Kateřina ; Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír ; Chýlková, J.
Electrochemical behavior of lecithin-cholesterol mixture in the form of phospholipid membranes (PLMs) was studied in this contribution. Lecithin (phosphatidylcholine) and cholesterol were chosen for this research, because they are essential for living cells. Electrochemical behavior of this system was studied using an electrochemical cell developed in our laboratory and with applying electrochemical impedance spectroscopy (EIS). Different ratios between lecithin and cholesterol placed on different polycarbonate substrates were tested. The influence of time and of temperature on formation of PLMs in presence of cholesterol was investigated.
Voltammetric Behavior of Folates and Related Substances Using Silver Solid Amalgam Electrode
Bandžuchová, L. ; Šelešovská, R. ; Navrátil, Tomáš ; Chýlková, J.
The possibility of application of silver solid amalgam electrode in voltammetric analysis of compounds with folate structure (folic acid, methotrexate, leucovorin) and substances, which play an important role in its metabolism (riboflavin, hydroxocobalamin) has been investigated. Cyclic voltammetry, DC voltammetry and Elimination voltammetry with linear scan has been used for study of voltammetric behavior of mentioned substances and for elucidation of electrochemical reactions. Differential pulse voltammetry has been applied for development of sensitive methods of determination for investigated electroactive compounds. The proposed methods were successfully applied for real samples analysis. Obtained results have been compared with those achieved using HMDE.
Construction and Application of Tubular Detector and Porous Flow-through Detector/Reactor of Silver Solid Amalgam for Electrochemical Measurements in Flow Systems
Josypčuk, Oksana ; Barek, J. ; Josypčuk, Bohdan
This paper presents the preparation and application of two new arrangements of silver solid amalgam (AgSA) electrodes for measurements in flow systems  tubular detector based on compact AgSA, and flow-through detector (or reactor) prepared from porous AgSA. Both electrodes were tested for electrochemical determinations of reducible inorganic (Cd2+, Zn2+) and organic (4-nitrophenol, lomustine) compounds under FIA with amperometric detection (Cd2+, Zn2+, 4-nitrophenol) and flow-DPV (lomustine). Furthermore, by combination of the porous reactor with immobilized enzyme and tubular detector the flow amperometric enzymatic biosensor was constructed for determination of glucose in a sample of honey and cholesterol and sarcosine in model samples.
Voltammetric Determination of Herbicide Triasulfuron using Mercury Meniscus Modified Silver Solid Amalgam Electrode
Bandžuchová, L. ; Šelešovská, R. ; Chýlková, J. ; Navrátil, Tomáš
Voltammetric behavior of triasulfuron (TS), which belongs to sulfonylurea herbicide family, was studied using two working electrodes: mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and hanging mercury drop electrode (HMDE) for comparison. It was found that TS provided one reduction peak on both used working electrodes. The highest response was observed in the environment of Britton-Robinson buffer (BR) of pH 3 (m-AgSAE) and 2.5 (HMDE), respectively. Working parameters of differential-pulse voltammetry (DPV) were optimized and this method was applied in analysis of agricultural formula and river water.

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