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Electrodeposited Coatings at ITO/FTO Enhancing their Applicability in Electroanalysis
Daňhel, Aleš ; Fojta, Miroslav
Recent possibilities of modification of transparent electrodes based on indium-tin oxide and/or fluorine doped tin oxide by electrodeposited coatings enhancing their electrochemical applicability in electroanalysis are discussed in this work. Ordered mesoporous silica and/or chemically functionalized mesoporous silica thin films may serve, among the common utilization in solid phase extraction, as protective layer of the electrode surface against its fouling and/or as molecular sieve permeable for small molecules and blocking large ones (DNA, proteins, etc.). Furthermore an electrodeposition of organic modifiers and/or metal (nano) particles inside of the ordered silica nanochanels together with direct electrodeposition of selected metal (nano) particles onto selected conductive transparent supports are presented here as well.
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Electrochemical Characterization of Poly(methylene Blue) Modified Graphite Electrodes
Zlámalová, Magda ; Janda, Pavel ; Nesměrák, K.
This work deals with electrochemical study of methylene blue (MB) polymerization as well as characterization of deposited conductive film on basal plane highly oriented pyrolytic graphite (HOPG) and pencil-graphite electrode (PGE). Poly(methylene blue) modified electrodes (HOPG/pMB and PGE/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing methylene blue monomer. It has been found that electrochemical properties and electrocatalytic activity of deposited film are greatly influenced by the type of electrode substrate. Developed electrodes have been further investigated as potential sensors for sulfhydryl-containing compounds.
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Lab-made Sensors Based on Boron-doped Diamond for Determination of Herbicide Linuron
Štěpánková, M. ; Šelešovská, R. ; Janíková, L. ; Vojs, M. ; Marton, M. ; Behúl, M. ; Nováková, Kateřina ; Chýlková, J.
Voltammetric behaviour of substituted urea herbicide linuron (LIN) was investigated using two types of boron-doped diamond electrodes (BDDE): commercial BDDE and lab-made sensors based on boron-doped diamond (LM-BDDE). Various methods like cyclic voltammetry (CV), direct current voltammetry (DCV) and differential pulse voltammetry (DPV) were examined. It was found that LIN provides one oxidation peak using all of the tested working electrodes and the highest current response was recorded in the acidic media. Thus, Britton-Robinson (B-R) buffer of pH 2 was used as a supporting electrolyte. Parameters of DPV were optimized and the low limits of detection (LOD) were reached 1.41×10−7 M for commercial boron-doped diamond electrode and 8.81×10−9 M, respectively, which represents the lowest LOD obtained for lab-made boron-doped diamond electrodes.
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Reduction and Oxidation of Hydroxyquinolines in Acetonitrile and Dimethylsulfoxide
Sokolová, Romana ; Ramešová, Šárka ; Fiedler, Jan ; Kolivoška, Viliam ; Degano, I. ; Gál, M. ; Szala, M. ; Nycz, J. E.
This study is focused on investigation of oxidation and reduction pathways of selected hydroxyquinoline compounds in nonaqueous solutions. The experimentally obtained reduction potentials are reported to well correlate with calculated values of LUMO energies as well as the obtained oxidation potentials are in a good agreement with theoretical HOMO energies. The cyclic voltammetry, in situ UV/Vis spectroelectrochemistry and in situ IR spectroelectrochemistry confirmed that the oxidation mechanism is complicated. Oxidation unexpectedly proceeds together with protonation of the starting compound. This behaviour was found for all studied compounds, hydroxyquinoline carboxylic acids and also for compounds, where a methyl group is present instead of carboxylic group.
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Influence of Cadmium on its Metabolism and Changes of Content of Nutritionally Important Compounds in Spring Barley
Paznocht, L. ; Vodičková, H. ; Phuong, L. M. ; Nováková, Kateřina ; Zámečníková, B. ; Kotíková, Z. ; Miholová, D. ; Navrátil, Tomáš
Very important agriculture products are cereals, which significantly contributes to securing of human nutrient needs. Cadmium is a toxic heavy metal, which is readily taken up and accumulated by plants in spite of its harmful effects. This metal cause a stress for the plants and results in many morphological, anatomical, physiological and biochemical changes. The effect of cadmium on the plant metabolism and changes in the content of nutritionally important compounds (protein and some metals – Fe, Zn, Cu, Mn content) was investigated. Results shown, that cadmium was effectively retained in the roots and content of studied compounds was influenced by present of cadmium in nutrient medium. In all the parts of cadmium-treated seedlings decrease in the iron content and increase in the zinc content (except of the first leaves) and decrease in the manganese content was found. The copper content in the root tissue increased by 112.1 %, on the other hand a significant decrease (by 44.4 % and 40.9 % respectively) in the first and the second leaves was observed. In the experimental varieties with cadmium in the concentration of 10-5 mol L-1, the content of soluble proteins was determined statistically higher in the root and basal parts than in the controlled varieties.
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Use of Silver Solid Amalgam Electrode for Determination of Acaricide Amitraz
Nováková, Kateřina ; Harvila, M. ; Navrátil, Tomáš ; Zima, J.
The electrochemical behavior of amitraz was studied at polished (p-AgSAE) and mercury meniscus modified (m-AgSAE) silver solid amalgam electrodes. The reaction mechanism was investigated using direct current voltammetry (DCV) and elimination voltammetry with linear scan (EVLS). The optimum conditions for differential pulse adsorption stripping voltammetry (DPAdSV) determination of amitraz were found in Britton-Robinson (BR) buffer mixed with ethanol in a volume ration of 1:4. DPAdSV with optimized parameters was applied for determination of amitraz in analyzed solutions. The limits of detection were calculated as 8.9 nmol L-1 (tacc = 20 s) for m-AgSAE and 0.168 mol L-1 (tacc = 20 s) for p-AgSAE. The proposed method was successfully applied for determination of this compound in real sample solutions.
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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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