The Polarographic Diffusion Current - Current-Time Relationship At The Dropping Mercury Electrode

1958 ◽  
Vol 58 (6) ◽  
pp. 1047-1079 ◽  
Author(s):  
Joseph M. Markowitz ◽  
Philip J. Elving
Keyword(s):  
Mercury Electrode ◽  
Diffusion Current ◽  
Current Time ◽  
Time Relationship ◽  
Dropping Mercury Electrode

A NOTE ON THE POLAROGRAPHIC ANALYSIS OF HYDROGEN PEROXIDE

1948 ◽  
Vol 26b (12) ◽  
pp. 767-772
Author(s):  
Paul A. Giguère ◽  
J. B. Jaillet
Keyword(s):  
Hydrogen Peroxide ◽  
Mercury Electrode ◽  
Limiting Current ◽  
Diffusion Current ◽  
Polarographic Analysis ◽  
Dropping Mercury Electrode ◽  
Strychnine Sulphate

The determination of hydrogen peroxide at concentrations higher than those normally covered in polarography was studied with various electrodes. The diffusion current was found to increase linearly with the peroxide concentration up to 0.15% with the dropping mercury electrode and up to nearly 1% with a fixed platinum microelectrode. Under these conditions the limiting current was about 10 times greater than that usually observed. Although the solutions were supersaturated with oxygen, traces of strychnine sulphate were sufficient to suppress all maxima.

Current-time characteristics of the rapidly dropping mercury electrode

1960 ◽  
Vol 23 ◽  
pp. 585-591 ◽  
Author(s):  
Reita Tamamushi ◽  
Sunao Momiyama ◽  
Nobuyuki Tanaka
Keyword(s):  
Mercury Electrode ◽  
Current Time ◽  
Dropping Mercury Electrode

A NOTE ON THE USE OF MULTI-TIP ELECTRODES IN POLAROGRAPHIC WORK

1947 ◽  
Vol 25b (2) ◽  
pp. 132-134 ◽  
Author(s):  
J. McGilvery ◽  
R. C. Hawkings ◽  
H. G. Thode
Keyword(s):  
Cathode Surface ◽  
Mercury Electrode ◽  
Diffusion Current ◽  
Calibration Constant ◽  
Limits Of Detection ◽  
The Past ◽  
Dropping Mercury Electrode

In the past, a dropping mercury electrode for polarographic work has consisted of a single capillary dipping in a solution. We have used two or more capillaries in parallel to increase cathode surface and thereby increase the diffusion current and the sensitivity of the instrument. The results indicate that each tip gives a diffusion current proportional to its calibration constant and that multi-tip electrodes give diffusion currents proportional to the sum of the capillary constants. Further, galvanometer oscillations are reduced considerably by the use of multi-tip electrodes. The use of multi-tip electrodes, therefore, makes it possible to extend the limits of detection and provides a means for reducing objectionable galvanometer oscillations.

Polarographic current-time curves and the Ilkovic Equation.

1958 ◽  
Vol 11 (3) ◽  
pp. 271 ◽  
Author(s):  
HA McKenzie
Keyword(s):  
Mercury Electrode ◽  
Potassium Nitrate ◽  
Current Time ◽  
Current Voltage ◽  
Modified Equations ◽  
Dropping Mercury Electrode ◽  
Instantaneous Current ◽  
Average Current ◽  
The One ◽  
Oxygen Measurements

The Ilkovic equation for the limiting diffusion current obtained with a dropping mercury electrode predicts that the instantaneous current grows during the life of the mercury drop as the one-sixth power of the time, and that the ratio of the instantaneous current at the end of the drop life (the maximum current) to the average current is 1.17. McKenzie (1948) showed in a preliminary study that these relations are not obeyed. The present paper is concerned with a more detailed study of current-time curves for cadmium(II), lead(II), and thallium(I) ions and oxygen. Measurements are made both in the presence and absence of maximum suppressor (gelatin) in two supporting electrolytes (potassium chloride and potassium nitrate). It is found that the rate of growth of the instantaneous current is not in accordance with the Ilkovic equation. Also, it does not accurately follow the modified equations, such as the Lingane-Loveridge equation, particularly during the early stages of drop life. The ratio of maximum to average current varies for the different electroactive substances, but in all cases examined 1.23<imax./iav.<1.30. An interesting observation is also made on the current-time curves for cadmium(II) in potassium nitrate in the presence of gelatin. At pH values appreciably below the isoelectric point (?pH 5) the current-time curves and the current-voltage curves are distorted. The implications of these results in the measurement of polarographic waves, both in theoretical and analytical applications, are discussed.

Polarography of azobenzene and its p-sulphonic acids

1964 ◽  
Vol 17 (10) ◽  
pp. 1085 ◽  
Author(s):  
TM Florence ◽  
YJ Farrar
Keyword(s):  
Ph Effect ◽  
Aqueous Media ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Ammonium Ions ◽  
Current Time ◽  
Electrode Processes ◽  
Ph Values ◽  
Strong Adsorption ◽  
Dropping Mercury Electrode

The behaviour at the dropping mercury electrode of trans-azobenzene and its p-sulphonic acids has been studied by several techniques including d.c., a.c., single sweep, and Kalousek polarography. Current-potential curves recorded at the streaming mercury electrode provided information on the reversibility of the electrode processes, while current-time and electrocapillary curves aided in elucidating the effects of adsorption. The results show that the rate of the electrode reaction of the azo-hydrazo couple is dependent on pH, the minimum rate occurring near pH 9 for azobenzene-4-sulphonic acid in aqueous media. At very low and high pH values, the couple approaches full reversibility at the dropping mercury electrode. This pH effect is apparently due to strong adsorption of both the azo and hydrazo derivatives near the potential of the electrocapillary maximum. Ammonium ions associate with azobenzene-4-sulphonate, and improve the reversibility in intermediate pH regions.

A Polarographic study of some Wurster salts

1958 ◽  
Vol 11 (2) ◽  
pp. 104 ◽  
Author(s):  
JA Friend ◽  
NK Roberts
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Formation Constant ◽  
Platinum Electrode ◽  
Mercury Electrode ◽  
Diffusion Current ◽  
Polarographic Study ◽  
Polarographic Investigation ◽  
Dropping Mercury Electrode ◽  
Hydrolysis Of

Four related Wurster salts are subjected to a polarographic investigation. In the case of Wurster's blue, results from the dropping mercury electrode, stationary platinum electrode, and rotated platinum electrode are compared. The Wurster salt of p-phenylenediamine is unstable in aqueous solution but is fairly stable in a mixture of methanol, acetic acid, and water and the decrease of diffusion current with time indicates a disproportionation. Wurster's red is also unstable in aqueous solution. In the solvent methanol, acetic acid, and water, a wave is observed with the stationary platinum electrode whose E� compares favourably with the potentiometric E?0. Evidence from the three types of electrodes mentioned previously indicates two one-electron waves for Wurster's blue. The semiquinone formation constant qualitatively appears much greater than that reported from potentiometric work. Decrease of diffusion current with time is perhaps due to a disproportionation (the very unstable di-imine has been shown to revert to the radical in aqueous solution). Polarographic waves given by the Wurster salt of diaminodurene suggest that the radical does not exist in aqueous solution. Waves corresponding to the original amine and duroquinone (formed by hydrolysis of the di-imine) are obtained.

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