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Information on Several Interesting Case Reports of Liquid Mercury Intoxication
Navrátil, Tomáš ; Vlčková, Š. ; Mrázová, K. ; Nováková, Kateřina ; Zakharov, S. ; Honsová, Š. ; Pelclová, D.
This contribution reports on several mercury non-professional intoxications. It can be summarized that it is very important to differentiate among forms of mercury which can (acute or chronic) endanger human health. Contrarily to the wide spread fears, liquid mercury represents low danger for men and for environment. Solid amalgams are probably the less toxic forms of mercury compounds. On the other hand, widely spread daily consumer goods can be very dangerous and toxic (saving balls, fluorescent tubes, etc.). Moreover, these goods are not marked as “toxic mercury containing”. The article discusses the instruction for removing mercury from our environment. Most of the reported data are based on database of the Czech Toxicological Information Centre (TIC) (from the years 1995 – 2015).
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Electrochemical Study of Oxazaborine Chromophores
Mikysek, T. ; Josefík, F. ; Vytřas, K. ; Ludvík, Jiří
This contribution describes a basic electrochemical study of a series of newly synthesized chromophores based on the oxazaborine core. The attention was focused on determination of the first oxidation and the first reduction potentials, their difference and the relationship to the calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies. The oxidation is mostly a two-electron irreversible process, the first reduction is also irrevesible, but involving one-electron. For better understanding of the relationship between the structure and redox properties, the approach using sigma (para) constants of Hammett type was applied, the difference between E(ox) and E(red) was correlated with the HOMO-LUMO gap.
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Comparison of Techniques for Single-Molecule Conductance Measurements of Expanded Pyridinium Molecules
Lachmanová, Štěpánka ; Hromadová, Magdaléna ; Sokolová, Romana ; Kocábová, Jana ; Gasior, Jindřich ; Mészáros, G. ; Lainé, P. P.
This work is focused on the comparison of two techniques of single-molecule conductance measurements: Scanning Tunneling Microscopy Break Junction technique and Mechanically Controlled Break Junction technique. The structure of studied compound 9-(pyridin-4-yl)benzo[c]benzo[1,2]quinolizino[3,4,5,6-ija][1,6]naphthyridin-15-ium allows the formation of the molecular bridge between two gold electrodes, which are connected to a source of the constant voltage in both of the used methods. The differences, advantages and disadvantages of both of the techniques will be discussed. Both techniques provided two values of conductance of studied compound depending on the experimantal conditions.
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Determination of Metallothioneins in the Liver of Small Terrestrial Mammals, Living at Hazardous Element Contaminated Sites
Křivská, D. ; Šestáková, Ivana
Animals living in the contaminated areas are exposed to elevated concentrations of risk elements. Pfibramsko is one of most contaminated sites in Czech Republic. This area is loaded with sources of geological and metallurgical industry influence resulting in extremely high Pb, Cd, and Zn contents in soil. We analyzed eighteen subjects trapped on selected locations around Kovohute Pribram, belonging to the species Apodemus sylvaticus and Microtus arvalis. By differential pulse voltammetry and modified Brdicka reaction were measured concentrations metallothionein (MT) in their livers. Differences of concentrations between measured MT contents were found between species and among places of trapping.
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Influence of Electrode Preparation on Electrocatalytic Activity of Tetrapyridinoporphyrazinato Cobalt(II) Complex to Propylene
Klusáčková, Monika ; Janda, Pavel ; Tarábková, Hana
The water-soluble complex N ,N' ,N' ',N' "-Tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt (CoTmt-3,4-ppa) has been deposited by different techniques on two substrate. Electrochemical deposition, spontaneous adsorption, and spin coating have been used to the modification of two electrode material: annealed gold as hydrophilic substrate and highly oriented pyrolytic graphite as hydrophobic substrate. The modified electrodes have been characterized using cyclic voltammetry, backscattering VIS spectroscopy and atomic force microscopy. The influence of substrate material and modification techniques on electrocatalytic activity of CoTmt-3,4-ppa modified electrodes for propylene oxidation has been studied.
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Noise Analysis of Ion Transfer Kinetics at the Micro Liquid/Liquid Interface
Josypčuk, Oksana ; Holub, Karel ; Mareček, Vladimír
Fluctuation analysis was utilized to determine the TEA ion transfer kinetics across the water/1,2-dichloroethane interface. The average value ks = 0.34 cm s-1 is comparable with the previously reported value ks = 0.2 cm s-1, derived from electrochemical impedance spectroscopy experiments. The experimental approach utilizing a thick wall glass microcapillary to fix the interface exhibits a very small stray capacitance value, proving this system to be suitable for determining the kinetics of the fast ion transfer across a liquid/ liquid interface. Application of a method employing a small perturbation signal prevents polarization of the inner capillary surface by current flowing through the cell. The induced polarization of the capillary can affect ion concentration at the interface due to electroosmosis and thus make the kinetics data evaluation difficult or erroneous.
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Electrochemical Biosensors Based on Silver Solid Amalgam for Analysis in Flow Systems
Josypčuk, Oksana ; Barek, J. ; Josypčuk, Bohdan
In this contribution, the construction and preparation of 3 types of flow amperometric enzymatic biosensors based on silver solid amalgam (AgSA) were presented. Two of them consist of the tubular detector and enzymatic reactor of porous or powdered AgSA. The third biosensor was constructed using polished AgSA electrode. Reactors and polished AgSA electrodes were modified with thiols or chitosan and different enzymes were covalently immobilized by suitable techniques. Prepared biosensors were used for determination of ascorbic acid, glucose, hydrogen peroxide, catechol, pyrogallol, dopamine and sarcosine in model samples and in same cases in the real samples.
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Unique Properties of Amalgam Electrodes
Josypčuk, Bohdan ; Josypčuk, Oksana
Depending on metal-mercury ratio and on the method of preparation amalgam can be: 1) solid compact; 2) paste; 3) liquid; 4) monocrystalline; 5) porous; 6) powdered. High potential of hydrogen overvoltage is observed on amalgam electrodes and it is comparable with one on Hg-electrodes. Another important benefit is the possibility to prepare amalgam electrode, detector or reactor of required size and shape. From amalgams have been prepared and tested many types of electrodes for batch and flow-through systems. The diversity of amalgam materials provides some unique electrochemical properties of electrodes, the most important of which are described in this paper.
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