Verification of a diffusion current equation accounting for convection and capillary shielding at the dropping mercury electrode

1978 ◽  
Vol 50 (14) ◽  
pp. 1980-1988 ◽  
Author(s):  
Timothy E. Cummings ◽  
Philip J. Elving
Keyword(s):  
Mercury Electrode ◽  
Diffusion Current ◽  
Dropping Mercury Electrode ◽  
Current Equation

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.

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.

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.

Electrochemical Studies on Eriochrome Violet B and Its Lanthanide Complexes. I. Behaviour of Eriochrome Violet B and Its Lanthanide Complexes at the Dropping Mercury Electrode: D.C., A.C., and Cathode Ray Polarography

1962 ◽  
Vol 15 (1) ◽  
pp. 65 ◽  
Author(s):  
TM Florence ◽  
GH Aylward
Keyword(s):  
Diffusion Coefficient ◽  
Atomic Number ◽  
Lanthanide Complexes ◽  
Mercury Electrode ◽  
Potential Difference ◽  
Diffusion Current ◽  
Electrochemical Studies ◽  
Polarographic Behaviour ◽  
Dropping Mercury Electrode

The polarographic behaviour of Eriochrome Violet B (5-sulpho-2-hydroxybenzene-azo-2-naphthol) and its lanthanide complexes has been investigated in some detail. Earlier workers found the dye to be reduced at the dropping mercury electrode in (I two-electron step to a stable hydrazo compound. The present work shows, however, that four electrons are involved in the reduction, and that the amines are the final reduction products. To explain the apparently anomalous polarographic behaviour of Eriochrome Violet B, a mechanism involving the disproportionation of an unstable hydrazo intermediate is proposed for the reduction. A diffusion current constant of 5 77 � 0.09 and a diffusion coefficient of 0.57 X cm2 sec-1 were found for the free dye in an ammonia buffer at 26 �C. The lanthanides combine with Eriochrome Violet B in a 1 : 2 ratio. These complexes produce discrete reduction steps which are separated from the free-dye step by a potential difference (ΔE) which depends on the atomic number of the lanthanide. In an ammonia buffer of pH 9.5 the ΔE values vary from 45 mV for lanthanum to 234 mV for lutetium.

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