Study of the EE mechanism with adsorption of the intermediate at spherical and planar electrodes following a Langmuir’s isotherm

1991 ◽  
Vol 56 (1) ◽  
pp. 60-67 ◽  
Author(s):  
María-Luisa Alcaraz ◽  
Jesús Gálvez
Keyword(s):  
Power Law ◽  
Mercury Electrode ◽  
Plane Electrode ◽  
Dropping Mercury Electrode ◽  
Planar Electrodes ◽  
Current Potential

The theory for the EE mechanism with adsorption of the intermediate following Langmuir’s isotherm has been developed for the expanding sphere with any power law electrode model. The equations obtained with this model are general and can be applied, for example, to a stationary plane electrode, to a stationary sphere electrode, and to the two models of dropping mercury electrode (DME), expanding plane and expanding sphere. The influence exerted by the sphericity of the electrode on the current-potential (I/E) curves and the characteristics of these curves are discussed.

THE DETERMINATION OF KINETIC PARAMETERS OF REDOX REACTIONS FROM CURRENT–POTENTIAL CURVES

1959 ◽  
Vol 37 (1) ◽  
pp. 238-246 ◽  
Author(s):  
J. E. B. Randles
Keyword(s):  
Kinetic Parameters ◽  
Redox Reactions ◽  
Mercury Electrode ◽  
Dropping Mercury Electrode ◽  
Mercury Electrodes ◽  
Rotating Electrodes ◽  
Current Potential ◽  
Potential Curves ◽  
Good Agreement

Methods are suggested for calculating kinetic parameters of moderately rapid redox reactions from current–potential curves obtained with (a) rotating electrodes or stationary electrodes in stirred solutions, (b) dropping mercury electrodes. Experimental results for the V2+/V3+ reaction at a dropping mercury electrode are presented and compared with a-c. impedance measurements on the same system. It is found that there is a good agreement between the kinetic parameters obtained by the two methods when the current–potential curves are interpreted with the aid of Koutecky's theory of diffusion to a dropping mercury electrode.

Reduction and tensammetric pulse-polarographic currents of polynucleotides

1987 ◽  
Vol 52 (11) ◽  
pp. 2810-2818 ◽  
Author(s):  
Emil Paleček ◽  
František Jelen ◽  
Vladimír Vetterl
Keyword(s):  
Diagnostic Criteria ◽  
Pulse Width ◽  
Mercury Electrode ◽  
Pulse Amplitude ◽  
Single Strand ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Adenylic Acid ◽  
Drop Time

The behaviour of electrochemically reducible single-strand polynucleotides (poly(adenylic acid)) and poly(cytidylic acid)) was studied by the differential (derivative) pulse polarography (DPP) and by other methods. Measurements were performed with the help of the dropping mercury electrode under various conditions specified by the pulse width, pulse amplitude, drop time etc. For the faradaic and tensammetric DPP peaks the diagnostic criteria were proposed which make it possible to classify even very small DPP peaks of double helical polynucleotides.

Determination of platinum in biological material by differential pulse polarography: Analysis in urine, plasma and tissue following sample combustion

1983 ◽  
Vol 48 (10) ◽  
pp. 2903-2908 ◽  
Author(s):  
Viktor Vrabec ◽  
Oldřich Vrána ◽  
Vladimír Kleinwächter
Keyword(s):  
Biological Material ◽  
Biological Fluid ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Linear Calibration ◽  
Catalytic Current ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode

A method is described for determining total platinum content in urine, blood plasma and tissues of patients or experimental animals receiving cis-dichlorodiamineplatinum(II). The method is based on drying and combustion of the biological material in a muffle furnace. The product of the combustion is dissolved successively in aqua regia, hydrochloric acid and ethylenediamine. The resulting platinum-ethylenediamine complex yields a catalytic current at a dropping mercury electrode allowing to determine platinum by differential pulse polarography. Platinum levels of c. 50-1 000 ng per ml of the biological fluid or per 0.5 g of a tissue can readily be analyzed with a linear calibration.

The reduction of cobalt (II) ion in thiocyanate media by pulse polarography

1983 ◽  
Vol 48 (2) ◽  
pp. 544-549 ◽  
Author(s):  
Jorge Alfredo Bolzan ◽  
Robert Tokoro
Keyword(s):  
Mercury Electrode ◽  
Thiocyanate Complex ◽  
Catalytic Wave ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Thiocyanate Concentration

The electroreduction of cobalt(II) in aqueous thiocyanate solutions at the dropping mercury electrode depends on the thiocyanate concentration. At [SCN-] = 0.3 mol/l the intermediate cobalt(I)-thiocyanate complex does exist electrokinetically and may be responsible for the appearance of a peaked catalytic wave. The predecessor species of this intermediate may be CoSCN+ and Co(SCN)2 in similarity to the behaviour of cobalt(II) with cyanide and azide ions.

Oxidation of hydrogen peroxide at the dropping mercury electrode

1984 ◽  
Vol 49 (10) ◽  
pp. 2320-2331 ◽  
Author(s):  
Miroslav Březina ◽  
Martin Wedell
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Anion ◽  
Ph Value ◽  
Mercury Electrode ◽  
Electrode Process ◽  
Electrochemical Processes ◽  
Dropping Mercury Electrode ◽  
Oxidation Of Hydrogen ◽  
Decreasing Ph ◽  
Rate Controlling Step

Reduction of oxygen and oxidation of hydrogen peroxide at the dropping mercury electrode are electrochemical processes strongly influenced both by the pH value and the anions in solution. With decreasing pH, both processes become irreversible, especially in the presence of anions with a negative φ2 potential of the diffusion part of the double layer. In the case of irreversible oxygen reduction, the concept that the rate-controlling step of the electrode process is the acceptance of the first electron with the formation of the superoxide anion, O2-, was substantiated. Oxidation of hydrogen peroxide becomes irreversible at a lower pH value than the reduction of oxygen. The slowest, i.e. rate-controlling step of the electrode process in borate buffers at pH 9-10 is the transfer of the second electron, i.e. oxidation of superoxide to oxygen.

Effects of Langmuirian adsorption on the potentiostatic response at spherical and planar electrodes

1991 ◽  
Vol 56 (1) ◽  
pp. 42-59 ◽  
Author(s):  
María-Luisa Alcaraz ◽  
Jesús Gálvez
Keyword(s):  
Power Law ◽  
Adsorption Process ◽  
Asymptotic Solutions ◽  
Planar Electrodes ◽  
Comparison Of The Results

Equations for a potentiostatic reaction with an adsorption process following Langmuir’s isotherm have been derived for the expanding sphere with any power law electrode model. This model is very general and includes, among others, the following ones: (a) stationary plane; (b) stationary sphere; (c) expanding plane; and (d) expanding sphere. Characteristics of these solutions and the behavior of the corresponding asymptotic solutions are discussed. A comparison of the results obtained for plane and spherical electrodes has also been performed.

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