Chronocoulometry Anson plot

Fig. 4 Chronocoulometry (a) typical charge response (b) Anson plot for a double-step chronocoulometric experiment.

Such a charge measurement procedure, known as chronocoulometry, is particularly useful for measuring the quantity of adsorbed reactants (because of the ability to separate the charges produced by the adsorbed and solution species). A plot of the charge (0 versus /12, known as an Anson plot, yields an intercept at t = 0 that corresponds to the sum of 0 and Qt (Fig. 3.2). The former can be estimated by subtracting the intercept obtained in an identical experiment carried out in the blank solution. 

Chronoamperometry, Chronocoulometry, and Chronopotentiometry, Fig. 4 Chronocoulometric charge versus (time) plot in the absence (1) and in the presence (2) of adsorption. The dashed, horiztmtal line represents the charge response in the absence of reactant. This representation is sometimes referred to as Anson plot in the literature... 

Chronocoulometry is a technique related to chronoamperometry in which a potential step is applied to the deposited polymer film and the integrated current response i.e., the charge is monitored as a function of time. It is customary to plot charge q versus t, which defines an Anson plot. The chronocoulometric response for a layer of finite thickness L is given by the following expression ... 

FIGURE 1.51. Anson plot for chronocoulometry, plot calculated from Eqn. 273. Same date as in Fig. 1.47. 

FIGURE 1.52. (a) Normalized modified Anson plot for chronocoulometry in a finite-diffusion space. The curve is calculated from Eqn. 275. (b) Schematic of T versus t plot to obtain Dcr-... 

---