Pulse polarography normal

More complete data are available from textbooks (e.g., Bard 1980) and from polarographic equipment suppliers (e.g., EG G Princeton Applied Research Application Briefs and Application Notes). 

Scale not constant for drop time and pulse time 

Current transient during pulse application (expanded scale) 

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Potential-excitation signals and voltammograms for (a) normal pulse polarography, (b) differential pulse polarography, (c) staircase polarography, and (d) square-wave polarography. See text for an explanation of the symbols. Current is sampled at the time intervals indicated by the solid circles ( ). 

The following data were collected for the reduction of Pb + by normal pulse polarography... 

Fig. 3.36. Normal pulse polarography, (a) sampling scheme, (b) current sampled. 

Holub, K. and van Leeuwen, H. P. (1984). Influence of reactant adsorption on limiting currents in normal pulse polarography. 2. Theory for the stationary, spherical electrode, J. Electroanal. Chem., 162, 55-65. 

The quasi-reversihle electroreduction processes of Zn(II) in the absence and in the presence of Ai,Ai -dimethylthiourea (DMTU) were quantitatively compared by Sanecld [91], It has been shown that in the presence of DMTU enhanced response of cyclic voltammetry and normal pulse polarography was complex and could be resolved into its regular reduction part and a part caused by the catalytic influence of adsorption of organic substance. 

Many of the experimental parameters for normal-pulse polarography are the same as with differential-pulse polarography. Differential-pulse polarography is a technique that uses a series of discrete potential steps rather than a linear potential ramp to optimize specific applications (130). Unlike normal-pulse polarography, each potential step has the same amplitude, whereas the return potential after each pulse is slightly negative of the potential prior to the step. In this manner, the total waveform applied to the dropping mercury electrode is very much like a combination of a linear ramp with a superimposed square wave. 

This method is classified into normal pulse polarography and differential pulse polarography, based on the modes of applied voltage [5]. 

Two electrochemical techniques are directly based on the expression for the faradaic current density jF, namely chronoamperometry and normal pulse polarography. A third technique, named chronocoulometry, deals with the integral of jF, giving the charge transferred per unit area via the faradaic process as a function of time. The general expression obtained... 

Although normal pulse polarography was developed mainly for analytical purposes, it is a valuable and simple method to study kinetics of not-too-fast electrode reactions. As the other controlled potential techniques, it has the advantage of being applicable to systems where only one of the redox components is present initially. The technique is closely related to d.c. polarography [11] and the expressions discussed in this section are directly applicable to the case of d.c. polarography performed with the static mercury drop electrode (SMDE) if the correction for the spherical shape of this electrode is negligible [21, 22]. 

The Dimensionless Parameter is a mathematical method to solve linear differential equations. It has been used in Electrochemistry in the resolution of Fick s second law differential equation. This method is based on the use of functional series in dimensionless variables—which are related both to the form of the differential equation and to its boundary conditions—to transform a partial differential equation into a series of total differential equations in terms of only one independent dimensionless variable. This method was extensively used by Koutecky and later by other authors [1-9], and has proven to be the most powerful to obtain explicit analytical solutions. In this appendix, this method will be applied to the study of a charge transfer reaction at spherical electrodes when the diffusion coefficients of both species are not equal. In this situation, the use of this procedure will lead us to a series of homogeneous total differential equations depending on the variable, v given in Eq. (A.l). In other more complex cases, this method leads to nonhomogeneous total differential equations (for example, the case of a reversible process in Normal Pulse Polarography at the DME or the solutions of several electrochemical processes in double pulse techniques). In these last situations, explicit analytical solutions have also been obtained, although they will not be treated here for the sake of simplicity. 

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