Effect of Fe(III) on specific adsorption of aliphatic carbamide derivatives at the dropping mercury electrode

1983 ◽  
Vol 48 (11) ◽  
pp. 3253-3260
Author(s):  
Joanna Masłowska ◽  
Halina Czerwinska
Keyword(s):  
Adsorption Isotherms ◽  
Adsorption Process ◽  
Mercury Electrode ◽  
Specific Adsorption ◽  
Frumkin’S Isotherm ◽  
Dropping Mercury Electrode ◽  
Free Molecules

The specific adsorption of carbamide and its aliphatic derivatives (L) was studied by the droptime method in the system Fe(ClO4)3-L-HClO4-H2O, and the adsorption process was elucidated. From the calculated surface concentrations and adsorption isotherms, it was found that the adsorption of aliphatic carbamide derivatives is higher in the presence of Fe(III) ions than in their absence under the same conditions. In the presence of Fe(III) ions at the interface, free molecules of carbamide derivatives and the complexes [Fe(H2O)6-nLn]3+ as well as the complexes [Fe(H2O)5-nLnLads]3+ and [Fe(H2O)5-nLnLads]2+ formed with the adsorbed ligand are adsorbed. The adsorption was found to proceed according to the Frumkin's isotherm.

Polarography of nickel in concentrated chloride media

1966 ◽  
Vol 19 (8) ◽  
pp. 1343 ◽  
Author(s):  
TM Florence
Keyword(s):  
Ionic Strength ◽  
Graphite Electrode ◽  
Supporting Electrolyte ◽  
Anhydrous Methanol ◽  
Pyrolytic Graphite ◽  
Hydration Number ◽  
Mercury Electrode ◽  
Specific Adsorption ◽  
Dropping Mercury Electrode ◽  
Pyrolytic Graphite Electrode

In concentrated chloride media, nickel is reduced at far more positive potentials than in dilute solutions. The positive shift in half-wave potential increases as the ionic strength is raised, and is also greater when the cation of the supporting electrolyte has a high hydration number. Evidence is presented to show that the reduction in overpotential is due to the formation of a nickel chloride complex, [Ni(H2O)5Cl]+, which has a stoicheiometric stability constant of 0.094 � 0.009 at an ionic strength of 10.0. Spectrophotometric results show that this nickel species is not formed in low ionic strength solutions. In anhydrous methanol saturated with lithium chloride, nickel is present as the tetrachloro complex, [NiCl,]2-, which has similar polarographic behaviour to the monochloro complex. Current-potential curves recorded at a rotated pyrolytic graphite electrode enabled the behaviour of nickel to be studied in the absence of specific adsorption of the chloride ion. Nickel is reduced at more positive potentials at a dropping mercury electrode than at the pyrolytic graphite electrode, and the results indicate that this difference is due to specific adsorption of chloride on the mercury electrode.

Alternating current polarography of organic compounds. V. Quantitative treatment of the adsorption process

1956 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
B Breyer ◽  
HH Bauer
Keyword(s):  
Organic Compounds ◽  
Adsorption Process ◽  
Adsorption Equilibrium ◽  
Mercury Electrode ◽  
Alternating Current ◽  
Qualitative Explanation ◽  
Calibration Curves ◽  
Adsorbent Surface ◽  
Dropping Mercury Electrode ◽  
Quantitative Treatment

Equations are derived to express the adsorption equilibrium subsisting at an adsorbent surface in the presence of two adsorbable species. These equations are applied to the case of the reduction of organic compounds at the dropping mercury electrode. It is well known that adsorption at the electrode can produce irreversibility in the D.C. step, and a qualitative explanation is provided. The same treatment is used to explain the shape of the A.C. calibration curves.

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.

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.

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