Fast cyclic voltametry

Therefore, the only way to obtain precise values is to use fast cyclic voltametry on model compounds, for example, the two trimethylated flavan-3-ols, which offer only one free function hydroxyl. The redox potential of each phenolic function using fast cyclic voltametry has been investigated [39] (Fig. 2) and is summarized in Table 3. 

DNA-dye assemblies provided a nearly reversible response at scan rates up to 500 mV s. Thus, electron transfer through the ds DNA and hexamethylenethiol linker was concluded to be fast on the electrochemical time scale. Similar conclusions were drawn from the cyclic voltametry of the electroactive intercalator daunomycin selectively bound to G C sites at varying locations within a duplex attached to the electrode surface with a 13-atom alkylamide tether [173c],... 

If the thickness of the chemically fixed gel is more than 10 times that of the electrode radius, the observed electrolysis current value reflects the concentration and the diiiusion coefficient of the solute within the gel. This allows us to ignore the concentration of the solute and its diiiusion coefficient in the solution in which the gel is immersed. If the measurement is taken in such a way as to follow the time scale of Eqs. (2) and (3), that is, if the slope in the relationship between / and in the region where the time dependence of the electrolysis current follows Eq. (2), C and D can be independently determined. This is possible because the unknown parameters in Eqs. (2) and (3) are only C and D. When the diiiusion coefficient is sufficiently fast, for example, the diiiusion coefficient of the solute in a swollen gel is around 10 -10 cm /s, the time scale which follows Eq. (2) is on the order of milliseconds and, thus, measurement becomes difficult In an ordinary electrochemical measurement, the mode of diiiusion becomes a combination of ID diiiusion and radiative diffusion. The response of cyclic voltametry for this mixture of diffusion modes has already been analyzed. 

When p is small (slow sweep, small radius of the electrode), Ip is the same as in Eq. (3). Therefore, by performing cyclic voltametry at various sweeping rates and obtaining the steady-state current, which is expressed by Eq. (3) for a sufficiently slow sweeping rate, and the peak current, which is expressed by Eqs. (4) and (5) for a fast sweeping rate, it is relatively easy to determine the concentration and diffusion coefficient of the solute in a gel. 

Rather, they show a specific peak in the middle. The time to exhibit this peak is shorter in the O electrode, and longer in the I electrode. Figure 11 shows the results of the individually determined D and C from the peak current value by fast sweep rate cyclic voltametry as a function of time, changing the solvent from water to 70% acetone solution and using the same gel-treated electrode. The current peak corresponds to the maximum of the diffusion coefficient of Fc and the time needed for this maximum to appear is less in the 0 electrode and more in the I electrode. Although it is not yet clear as to why the maximum appears in the diffusion coefficient, it is hypothesized that it relates to the exchange process of the solvent from... 

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