Supporting electrolyte in polarography

Vecchi E., Zuliani G. Molting Carbamide Supporting Electrolyte in Polarography. Ric. Sci., 1955 25 2667-69. 

C15. Christian, G. D., Knoblock, E. C., and Purdy, W. C., Use of highly acid supporting electrolytes in polarography. Observed changes in polarographic waves of selenium (IV) upon standing. And. Chem. 37, 425- 27 (1965). 

Moe, N.S., Tetraethyl ammonium fluoroborate as a supporting electrolyte in polarography, Acta Chem. Scand. 19,1023-1024 (1965). 

Electrochemical measurements especially in polarography and cyclic voltammetry are frequently carried out in the presence of a supporting electrolyte. Concentrations of the supporting electrolyte in aqueous and nonaqueous solutions are usually 0.1 mol dm , but may reach 1 mol dm or more. Analysis of activity coefficients for the salt under study is not possible. Conductance studies in nonaqueous solvents... 

The electrochemical behavior of niclosamide was described on the basis of d.c. polarography, cyclic voltammetry, a.c. polarography, and differential pulse polar-ography, in the supported electrolytes of pH ranging from 2.0 to 12.0 [32], A tentative mechanism for the reduction of niclosamide is proposed that involves the transfer of 4 e . Parameters such as diffusion coefficients and heterogeneous forward rate constant values were evaluated. 

The real forward rate constant was estimated to be kf, - = 3.9 x 10 mol Ls at r = 25°C in 1 mol/L KNO3 as a supporting electrolyte. This value is iu good agreemeut with the values measured with cyclic voltauunetiy and differential pulse polarography [65]. 

The existence of various oxidation states of technetium indicates the possibility of using polarography for its quantitative determination. Polarographic reduction of the pertechnetate ion at a dropping mercury electrode has been studied in different supporting electrolytes . 

The double-layer influence on the electrode reaction of Zn(II)/Zn(Hg) on DME in NaNOs solutions was studied in the concentration range from 0.01 to 1 M, using dc and ac polarography [30]. The apparent rate constants of the Zn(II)/Zn(Hg) system increase with dilution of the NaN03 supporting electrolyte. However, after the Frumkin correction, the rate constant was virtually independent of the supporting electrolyte concentration. 

Supporting electrolyte, 1190, 1216,1235 Surface area of drop, in polarography, 1244 Surface concentration, 805 Surface coverage, 933... 

If we measure a residual current-potential curve by adding an appropriate supporting electrolyte to the purified solvent, we can detect and determine the electroactive impurities contained in the solution. In Fig. 10.2, the peroxide fonned after the purification of HMPA was detected by polarography. Polarography and voltammetry are also used to determine the applicable potential ranges and how they are influenced by impurities (see Fig. 10.1). These methods are the most straightforward for testing solvents to be used in electrochemical measurements. 

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