Chronoamperometry stripping

Figure 6.2 (a) Stripping chronoamperometry current transients for the oxidation of a saturated... 

The potential of the stripping peak, and hence the activity of the electrode for CO oxidation, also depends on the platinum surface structure in general and on the step density in particular. Based on the chronoamperometry experiments described in Section 6.2.1.1, one would expect the stripping peak to shift to lower potential with increasing step density. That this is indeed the case is shown in Fig. 6.6. Again, this... 

CA—chronoamperometry, CV—cyclic voltammetry, SWV—square wave voltammetry, ASV—anodic stripping voltammetry, SHE—standard hydrogen electrode. 

Chronoamperometry is often used for measuring the diffusion coefficient of electroactive species or the surface area of the working electrode. Some analytical applications of chronoamperometry (e.g., in vivo bioanalysis) rely on pulsing of the potential of the working electrode repetitively at fixed time intervals. Some popular test strips for blood glucose (discussed in Chapter 6) involve potential-step measurements of an enzymatically liberated product (in connection with a preceding incubation reaction). Chronoamperometry can also be applied to the study of mechanisms of electrode processes. Particularly attractive for this task are reversal double-step chronoamperometric experiments (where the second step is used to probe the fate of a species generated in the first one). 

Finally, US-enhanced mass transport has also been found to influence the rate of metal deposition (e.g. that of cobalt on glassy carbon electrodes by cyclic and stripping voltammetry, and chronoamperometry [157]). 

Terminology related to electroanalytical chemistry are chronoamperometry, voltammetry, coulometry, amperometric titrimetry, coulometric titrimetry, conductivity, con-ductimetry and high frequency titrimetry, electrometric titrimetry, electrogravimetry, electrodeposition, anodic stripping voltammetry (ASV), cathodic stripping voltammetry (CSV), polarography, differentia] pulse polarography (DPP), ion-selective electrode (ISE), ion-specific electrode (ISE), molecular selective electrode, potentiometry, potentio-metric titrimetry, and chronopotentiometric titrimetry. 

Thermodynamically it is the total charge balance of the adsorbed ion and co-adsorption of counter ions. The value can be obtained by independent measurements of adsorbed charge and adsorbed mass. The charge is usually determined by chronoamperometry and integration of potential scans either in the negative direction (adsorption) or the positive one (desorption and anodic stripping method). The latter method is usually preferred because the adsorption film reaches a stable condition. The mass can be determined by several methods. The experimental techniques and examples will be described in Section 4.2. 

The majority of measurements for electroanalysis with microelectrodes are recorded under steady-state conditions by using either chronoamperometry (CA), linear sweep voltammetry (LSV) or cyclic voltammetry (CV) [1,2, 9,10]. Moreover, to solve problems related to the selectivity between species with similar redox potentials, pulsed techniques such as differential pulse voltammetry (DPV) [1, 7, 43 5] and square-wave voltammetry (SWV) [1, 45-49] have been employed. The use of the latter technique also minimizes the influence of oxygen in aerated natural samples [47]. In order to enhance sensitivity in these measurements, fast-scan voltammetry (FSV) [50] or the accumulation of analytes onto an electrode surface has also been performed, in conjunction with stripping analysis (SA) [51]. 

Antibody membrane electrodes were characterized using cyclic voltammetry (CV), chronoamperometry (CA) and ELISA protocols. The electrolyte solution used for the CV consisted of 0.1 M phosphate buffer saline (PBS) at pH 7.4, 0.1 M NaCl and 0.1 M NaHC03. The ELISA test was conducted to assess the bioactivity of the antibody protein incorporated into the polymers. This was performed directly on the polymers deposited on platinum strips, which were coated on polyester and prepared as described above. A section of the polymer was removed from the bulk using a hole puncher and was placed in the bottom of microtitre plates for ELISA analysis. The plates were read at 405 nm every 10-minute interval. 

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