The Experts below are selected from a list of 4068 Experts worldwide ranked by ideXlab platform
Petr Zuman - One of the best experts on this subject based on the ideXlab platform.
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electroanalysis in biomedical and pharmaceutical sciences voltammetry amperometry biosensors applications
2015Co-Authors: Sibel A Ozkan, Petr Zuman, Jeanmichel Kauffmann, Ana Maria Oliveira BrettAbstract:Introduction.- Polarography in Studies of Pharmaceuticals.- Electroanalytical Techniques Most Frequently Used in Drug Analysis.- Solid Electrodes in Drug Analysis.- Screen Printed Electrodes (SPE) for Drug Compounds Determination.- Electrochemical Biosensors for Drug Analysis.- Electrochemical and hyphenated electrochemical detectors in liquid chromatography and flow injection systems for drug compound analysis.- Electroanalytical Methods Validation in Pharmaceutical Analysis and Their Applications.- Applications for Drug Assays.
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j heyrovský japan and organic Polarography
Chemical Record, 2012Co-Authors: Petr ZumanAbstract:Polarography is an electroanalytical technique based on recording current-voltage curves using a dropping mercury as the working electrode. It can be used for investigations of both reductions and oxidations of inorganic and organic species. Before WWII the developments of this technique linked Prague (in the then Czechoslovakia) with Kyoto (in Japan, where reductions of organic compounds were first observed). After WWII wide use of this technique has developed, so that in the 1950s and 1960 it became the fifth most frequently used analytical technique. More recently the analytical applications were limited to those of heterogeneous solutions and analyses of some drugs. Its applications in physical organic chemistry involve studies of structure-reactivity relationships and applications to investigations of equilibria and kinetics of rapidly or slowly established processes. DOI 10.1002/tcr.201100042
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Reduction of two isomeric oximes of aryl alkyl 1,2-diketones: Difference in products formed in Polarography and controlled potential electrolysis
Elsevier, 2006Co-Authors: Hayati Celik, Jiri Ludvik, Petr ZumanAbstract:At pH lower than 5 under conditions of d.c. Polarography and cyclic voltammetry the oxime PhCOC(=NOH)CH3 does not yield the expected reducible α-aminoketone, but rather a non-reducible olefin derivative. Its formation is attributed to a reduction of a diprotonated form of a ketoimine intermediate. In the same pH-range under conditions of controlled potential electrolysis the olefin derivative is slowly converted in a homogeneous reaction into a reducible α-aminoketone. Keywords: Polarography, Cyclic voltammetry, Controlled potential electrolysis, Reaction intermediates, Tautomer
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half a century of research using Polarography
Microchemical Journal, 1997Co-Authors: Petr ZumanAbstract:Abstract Polarography has been used in investigations of equilibria between carbonyl compounds and Schiff bases. Formation of mercury compounds of thiols, some urea, and thiourea derivatives is manifested by anodic polarographic waves. Electrochemical data for numerous organic compounds can be correlated with structural parameters using LFERs. Such correlations can be used in mechanistic studies and in choice of representative model compounds. For organic compounds bearing two electroactive centers the degree of their mutual interaction is reflected by their electrochemical behavior. Such interactions range from weak to medium strength (manifested by substituent effects) to strong interactions (resulting in changes in mechanisms of electrode processes). Strong interactions may result in reversal of the sequence of the reducibility of the two electroactive groups. Changes of polarographic current–voltage curves with solution composition enable determination of equilibrium constants for rapidly and slowly established equilibria preceding electron transfer. From currents governed by homogeneous antecedent reactions rate constants of fast reactions (between 10 4 and 10 10 l mol −1 s −1 ) can be obtained. For slower reactions occurring in the bulk of the solution variations of currents with time are used in kinetic studies. Polarographic measurements can be carried out directly in the reaction mixture and are complementary to spectrophotometry. Kinetics can be followed polarographically even in heterogeneous systems. This was used in studies of formation of slightly soluble complexes, e.g., of heavy metal ions with BAL and bile salts. Adsorption of organic (e.g., pesticides) and inorganic species on lignin can be followed, as well as formation of aromatic aldehydes and unsaturated ketones in alkaline cleavage of lignin. Examples of practical applications of polarographic analysis in food chemistry and pharmaceutical and medical science are given.
Arnold G Fogg - One of the best experts on this subject based on the ideXlab platform.
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Polarography and voltammetry at mercury electrodes
Critical Reviews in Analytical Chemistry, 2001Co-Authors: Jiři Barek, Arnold G Fogg, Alexandr Muck, Jiři ZimaAbstract:Scope and limitations of modern polarographic and voltammetric techniques on mercury electrodes are discussed and many practical examples of their applications in practical analysis are given to demonstrate that even in the third millennium Polarography and voltammetry at mercury electrodes can be very useful analytical tools, which in certain cases can successfully compete with modern spectroscopic and separation techniques.
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electrochemical reduction at mercury electrodes and differential pulse polarographic determination of pentamidine isethionate
Analyst, 1993Co-Authors: Valnice M B Zanoni, Arnold G FoggAbstract:Reduction processes are observed for pentamidine isethionate at a dropping mercury electrode above pH 7: the reduction potential is independent of pH below about pH 10. Below pH 10, adsorption of the reduced species is observed, whereas above pH 10 there is a large contribution owing to adsorption of pentamidine isethionate. For the polarographic determination of pentamidine isethionate, a pH of 8–9 is recommended with the addition of Triton X-100 as a maximum suppressor. Pentamidine isethionate can be determined by differential-pulse Polarography down to about 5 × 10–6 mol l–1.
Hirosuke Tatsumi - One of the best experts on this subject based on the ideXlab platform.
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Inkjet Polarography
'Elsevier BV', 2021Co-Authors: Xianmei Liu, Takuya Okada, Fumiki Takahashi, Jiye Jin, Hirosuke TatsumiAbstract:A single nozzle piezoelectric inkjet device was introduced for Polarography using a dropping carbon fluid electrode (DCFE). The viscosity of the carbon fluid prepared by mixing a spherical graphite powder and a perfluoroalkane oil was low enough for it to be ejected by the inkjet system. The periodic renewal of the DCFE was achieved at a frequency of 1 Hz with a constant droplet size (about 2 mm). A polarogram of ferrocenecarboxylate with a limiting current was observed
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development of dropping carbon fluid electrodes for Polarography
Electrochimica Acta, 2014Co-Authors: Hirosuke Tatsumi, Shogo TanakaAbstract:Abstract Another type of Polarography was investigated using a dropping carbon fluid electrode composed of graphite powder and a mixture of dioctyl phthalate and diiodomethane. The reproducibility of the drop size was improved by changing the tip of capillary and the composition of carbon fluid. Polarograms with clear limiting currents were observed when the concentration of reactant, ferrocenecarboxylate (FcCOO − ), was lower than 80 μM. The dependence of the limiting currents on the flow rate of the electrode and the concentration of FcCOO − were approximately consistent with the prediction from Ilkovic equation.
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Polarography with a dropping carbon electrode
Electrochemistry Communications, 2012Co-Authors: Hirosuke Tatsumi, Minami ShibaAbstract:Abstract Fluid carbon electrodes for Polarography were studied. A mixture of dioctyl phthalate and diiodomethane was found to be suitable to prepare a dropping carbon electrode. With this dropping electrode, anodic Polarography of ferrocenecarboxylate in aqueous solution was performed at room temperature.
Minami Shiba - One of the best experts on this subject based on the ideXlab platform.
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Polarography with a dropping carbon electrode
Electrochemistry Communications, 2012Co-Authors: Hirosuke Tatsumi, Minami ShibaAbstract:Abstract Fluid carbon electrodes for Polarography were studied. A mixture of dioctyl phthalate and diiodomethane was found to be suitable to prepare a dropping carbon electrode. With this dropping electrode, anodic Polarography of ferrocenecarboxylate in aqueous solution was performed at room temperature.
Jayarama S Reddy - One of the best experts on this subject based on the ideXlab platform.
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estimation of cephalosporin antibiotics by differential pulse Polarography
Talanta, 1997Co-Authors: G Subba V Reddy, Jayarama S ReddyAbstract:Abstract Differential pulse polarographic (DPP) method of determination of cephalosporins has been developed based on the electrochemistry of the azomethine group in the drugs in universal buffers of pH 2.0–12.0. Quantitative measurements were successful in the concentration range of 1.0 × 10 −5 M–2.5 × 10 −8 M, the lower concentration representing the detection limit by DPP. The described procedure has been applied for the determination of these drugs individually in pharmaceutical formulations and urine samples as well as for simultaneous determination in a single run.