5/2010 Sensing in Electroanalysis
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/38130
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Článek Otevřený přístup peer-reviewedpublished Amperometric and spectrophotometric detection of aminobiphenyls and aminonaphthalenes in HPLC(Univerzita Pardubice, 2010) Zavázalová, Jaroslava; Dejmková, Hana; Ramešová, Šárka; Barek, Jiří; Pecková, KarolinaA new method for the determination of selected aminobiphenyls (ABs) and aminonaphthalenes (ANs), proved or suspected carcinogens and mutagens, was developed using reversed-phase HPLC coupled to an amperometric platinum tubular detector and a spectrophotometric detector. Using mobile phase consisting of acetonitrile and phosphate buffer pH 2.5 (40:60, v/v), separation of 2- and 4-aminobiphenyl and 1- and 2-aminonaphthalene was achieved within 10 min and limits of determination between 3·10–8 mol L–1 and 8·10–8 mol L–1 were obtained for amperometric detection. In comparison with spectrophotometric detection, it is superior in both sensitivity and selectivity. The developed method was applied on the analysis of spiked samples of urine. Solid phase extraction was used for a preliminary separation and preconcentration of the tested analytes, leading to the decrease of limits of determination to the values between 7.2·10–9 mol L–1 and 2.7·10–8 mol L–1.Článek Otevřený přístup peer-reviewedpublished Possibilities and limitations of ionic liquids in electrochemical and electroanalytical measurements (a review)(Univerzita Pardubice, 2010) Weidlich, Tomáš; Stočes, Matěj; Švancara, IvanA review (with 155 refs.) concerning the current achievements and typical trends in the chemistry of (room temperature) ionic liquids, (RT)ILs, with particular emphasis on their applicability in electrochemical and electroanalytical measurements. The latter is documented on a rapid progress of ionic liquid-modified carbon paste electrodes (IL-CPEs), the so-called carbon ionic liquid electrodes (CILEs), and related configurations in the last half-decade, within the period of 2005-2010.Článek Otevřený přístup peer-reviewedpublished Silver amalgam electrodes – a look back at the last five years of their development and applications(Univerzita Pardubice, 2010) Vyskočil, Vlastimil; Daňhel, Aleš; Fischer, Jan; Novotný, Vít; Deýlová, Dana; Horáková, Eva; Barek, Jiří; Yosypchuk, Bogdan; Wang, JosephDifferent types of silver amalgam electrodes have been introduced as modern and promising replacements for traditional mercury electrodes. Advantages and possibilities of these novel electrode materials were highlighted and demonstrated at a number of sensitive voltammetric and amperometric (HPLC, flow injection analysis) methods developed in our UNESCO Laboratory of Environmental Electrochemistry in the last five years. The determined analytes were hazardous organic chemical carcinogens and genotoxic environmental pollutants, pesticides, antitumor, antibiotic and antivirotic drugs, and explosives containing electrochemically reducible nitro, nitroso, azido, and oxo groups.Článek Otevřený přístup peer-reviewedpublished Wood-free resin pencil as low-cost electrode for pH measurements(Univerzita Pardubice, 2010) Urbanová, Veronika; Bartoš, Martin; Borecká, Daniela; Vytřas, KarelWe report on possible use of wood-free resin pencil (WPE) as low-cost pH electrode based on WPE coated by antimony or bismuth film as the main pH sensitive material. Sensors prepared allowed to measure pH in the range of 3-10 and 10-13. The pH electrodes proposed can take advantage in strong alkaline and corrosive systems where the use of traditional glass electrode is limited. Also, they can serve as the low-cost indicator electrodes in acid-base titrations.Článek Otevřený přístup peer-reviewedpublished Electrochemical sensing in elimination voltammetry(Univerzita Pardubice, 2010) Trnková, Libuše; Kizek, René; Adam, Vojtěch; Eckschlager, Tomáš; Hubálek, JaromírElimination voltammetry with linear scan (EVLS) represents the fast and simple improvement of linear-sweep or cyclic voltammetric results. Through the various elimination functions, EVLS offers a new tool not also for better understanding of complex electrochemical processes on the surface of working electrodes, but also for improving the sensitivity of electrochemical measurements. The paper is mainly focused on the elimination function 'E4', which eliminates the kinetic and charging current components and conserves the diffusion one from a total current measured. It was found that this function has the most sensitive and separation ability in the case of adsorptive electroactive species. The strength of combination of EVLS with an adsorptive stripping technique was demonstrated by the enhancement and resolution of overlapped reduction signals of adenine and cytosine residues in short synthetic oligonucleotides (ODN) and DNA at the hanging mercury drop electrode. Two EVLS modes single and double are presented and their detection capabilities in analytical systems discussed.Článek Otevřený přístup peer-reviewedpublished Carbon paste electrodes modified with a reaction product obtained by hydrolysis of an antimony(III) salt(Univerzita Pardubice, 2010) Švancara, Ivan; Florescu, Monica; Stočes, Matěj; Baldrianová, Lucie; Svobodová, Eva; Badea, MihaelaIn this article, a new type of antimony-modified electrode is described based on carbon-paste bulk dispersion of a precipitate obtained by hydrolysis of the respective Sb(III) salt. Subsequently, the resultant electrode (SbOL-CPE in two variants) operated via the antimony film formed in nascenti at the electrode surface was subjected to the basic characterisation with respect to its electroanalytical performance in the anodic stripping voltammetry of six heavy metal ions (Zn2+, Cd2+, Pb2+, Sn2+, In3+, and Tl+). As found out, the electrodes of interest have offered the behaviour and functioning comparable to the two related configurations of antimony film-plated (in situ) and antimony trioxide-modified carbon paste electrodes (SbFCPE and Sb2O3-CPE, respectively). Most importantly, the bulk modification with laboratory-prepared precipitate has been shown sufficiently reliable and the compound itself fairly reducible with stable behaviour; i.e., without need to refine or otherwise specially treat prior to use.Článek Otevřený přístup peer-reviewedpublished Conductometric and 1H NMR determination of the critical micellar concentrations of two oxo-derivatives of cholic acid. Which of the two is more hydrophobic?(Univerzita Pardubice, 2010) Poša, Mihaulj; Guzsvány, Valeria; Csanádi, JánosCritical micellar concentrations (CMCs) were determined for two novel promoters of membrane permeability – 7-monoketocholic acid (7-MKC) and 12- monoketocholic acid (12-MKC), using two non-invasive (conductometry and 1H NMR relaxation experiment) methods. Studies by these methods suggest the different aggregation abilities of the investigated bile acid derivatives. In an aqueous solution, 7-MKC has a somewhat lower CMC value (43 mM) than 12-MKC (50 mM). Further, it was found that, in addition to the primary micelles, 7-MKC forms also secondary micelles. Based on the CMC value 7-MKC is more hydrophobic than 12-MKC, although the opposite data can be found in the literature. The apparent hydrophobicity of 7-MKC is a consequence of the formation of secondary micelles, shifting the monomer equilibrium to the direction of first micelles, which is manifested as a decrease in the CMC value.Článek Otevřený přístup peer-reviewedpublished Amperometric detection of dissolved methanol using microelectrodes(Univerzita Pardubice, 2010) Papadimitriou, Sofia; Jiannakoudakis, Andreas; Sotiropoulos, SotirisWe report on the development of a simple amperometric method for monitoring of dissolved methanol in 0.5 M – 5 M solutions in sulfuric acid (relevant to methanol levels in the feed of direct methanol fuel cells) using bare Pt microdisc electrodes. The high mass transport rates of electroactive species to the microdisc from the solution phase results in a shift of the dissolved oxygen reduction wave to more negative potentials so that it does not interfere with the main methanol oxidation peak at sufficiently positive potentials (+0.5 - +0.7 V vs. Ag/AgCl). For continuous monitoring of methanol a potential sequence consisting of +1.6 V for 10s (cleaning pulse) / 0 V for 120 s (equilibration pulse) / +0.6 V for 180 s (measurement pulse) is applied to the indicator electrode, resulting in current-time transients that are reproducible upon periodic application for at least 8 h. There is a square root correlation between the oxidation current at +0.6 V and methanol concentration for the dissolved methanol sensor in the 0.5–3 M range, in accordance with theoretical predictions, thus excluding electrode poisoning/current saturation up to 3 M . The detection limit was estimated as 0.19 M making this simple method applicable for rough estimates and a crude monitoring of methanol levels.Článek Otevřený přístup peer-reviewedpublished Disposable screen-printed electrodes with in-built bismuth precursors for lead(II) determination by anodic stripping voltammetry(Univerzita Pardubice, 2010) Palogou, Christina; Mardakiouti, Efthymia; Economou, Anastasios; Kostaki, Vasiliki; Prodromidis, MamantosThe utility of disposable screen-printed electrodes modified with three bismuth-precursor compounds (bismuth titanate, bismuth oxide and bismuth aluminate) was assesed for the determination of Pb(II) by anodic stripping voltammetry. It was found that, in principle, both bismuth oxide and bismuth aluminate could be sucessfully used as bismuth precursors but the latter yielded higher sensitivity for the detection of Pb(II). The instrumental parametrs for Pb(II) determination (deposition time and potential and stripping waveform mode) were investigated and the effect of different co-existing metals was studied. Using the selected conditions, the limit of detection for Pb(II) was 0.6 μg l−1 and the % relative standard deviation at the 20 μg l−1 level was 5.2 % (n=8). The sensors were succcesfully utilised for the determination of Pb(II) in tap-water.Článek Otevřený přístup peer-reviewedpublished Comparison of lead dioxide and cerium dioxide as mediators for carbon paste electrodes in flow injection-amperometric detection of hydrogen peroxide(Univerzita Pardubice, 2010) Mihić-Necin, Bojana; Guzsvány, Valéria; Kalcher, KurtCarbon paste electrodes (graphite / paraffin oil), bulk-modified with lead dioxide and cerium dioxide, were used as sensors for the amperometric determination of hydrogen peroxide in flow injection analysis. Experimental parameters, such as applied working potential, flow rate of the carrier and injection volume were optimized with a thin-layer flow-through cell. The method was validated with respect to calibration curve, linear dynamic range, detection limit, repeatability and reproducibility.