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Reproducibility of working electrodes in voltammetry
Josypčuk, Bohdan ; Heyrovský, Michael
In voltammetry the working electrode is the source of signal from which the due information is gained. A transition from the dropping mercury electrode to any kind of stationary electrode is inevitably accompanied by worsened reproducibility of measurements, the transition to the hanging mercury drop electrode is accompanied by a certain instrumental complication. When solving a concrete task, the precision of reproducibility of measurements often becomes the decisive factor for selecting a particular type of working electrode, or for taking voltammetry as the method of choice. This work is the beginning of a wider study which includes comparison of different working electrodes and finding of optimal conditions guaranteed reproducible measurements of various electrode processes (reduction, oxidation, accumulation, adsorption and catalysis).
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Voltammetric measurement of H.sub.2./sub.O.sub.2./sub. concentration in aqua-organic solutions
Kurc, L. ; Floriš, T. ; Josypčuk, Bohdan
In this work was tested the applicability of voltammetry and of meniscus silver solid amalgam electrode for determination H2O2 in presence of organic species (solvent, substrate or product of Baeyer-Villiger oxidation of cycloketones to lactones). Hydrogen peroxide can be measured in its wide concentration interval in different aqua-organic solutions. The slope of H.sub.2./sub.O.sub.2./sub. concentration dependence decreases with increasing 1,4-dioxane concentration. 1,4-dioxane in mixture with water can be used up to its concentration 80 vol. %. Model species, which represent reactants and products of Baeyer-Villiger oxidation, influence calibration dependence individually and their effect is not possible to estimate. Hence, quantitative hydrogen peroxide determination in probes of reactive mixture, which have different composition, should be carried out by standard addition method.
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The Application of Silver Amalgam Electrode in Voltammetric Determination of Cd, Pb and Cu in Reference Materials of Plant Origin
Čížková, P. ; Šestáková, Ivana ; Josypčuk, Bohdan
Silver solid amalgam electrode, combined with PC-controlled regeneration of its surface, was successful in voltammetric analysis of Cd, Pb and Cu in certified reference materials BCR (Rye Gras) , 679 White Cabbage and other two candidate materials. Results were compared and statistically evaluated with those obtained by voltammetry on HMDE and ETA-AAS determination. Silver solid amalgam electrode, combined with PC-controlled regeneration of its surface, was successful in voltammetric analysis of Cd, Pb and Cu in certified reference materials BCR (Rye Gras) , 679 White Cabbage and other two candidate materials. Results were compared and statistically evaluated with those obtained by voltammetry on HMDE and ETA-AAS determination.
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Ink Films from Carbon Powders on Conventional Solid Electrodes as Alternative Disposable Sensors
Josypčuk, Bohdan ; Barek, J. ; Novotný, Ladislav
Rozšíření rozsahu pracovních potenciálů pevných elektrod bylo docíleno jejich pokrytím filmem z polymeru obsahujícího vodivé částice (grafitu, skelného uhlíku, nanotub aj.). Takový film může obsahovat 70 - 90% skelného uhlíku a 30 - 10% polystyrenu (procenta hmotnostní). Film se 70 % skelného uhlíku se chová více jako soubor mikroelektrod; s 90 % - spíše jako klasická elektroda ze skelného uhlíku. S takovým filmem lze pracovat i celý den; pro odstranění filmu stačí otřít ho o filtrační papír. Pro oxidaci ferocenu, adeninu, guaninu a jiných látek byly použity filmy s různým obsahem skelného uhlíku na podložkách ze stříbrného pevného amalgamu, zlata a platiny.
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