Hydrodynamic voltammograms operating potentials

LCEC is a special case of hydrodynamic chronoamperometry (measuring current as a function of time at a fixed electrode potential in a flowing or stirred solution). In order to fully understand the operation of electrochemical detectors, it is necessary to also appreciate hydrodynamic voltammetry. Hydrodynamic voltammetry, from which amperometry is derived, is a steady-state technique in which the electrode potential is scanned while the solution is stirred and the current is plotted as a function of the potential. Idealized hydrodynamic voltammograms (HDVs) for the case of electrolyte solution (mobile phase) alone and with an oxidizable species added are shown in Fig. 9. The HDV of a compound begins at a potential where the compound is not electroactive and therefore no faradaic current occurs, goes through a region... 

The differences between the diffusion-controlled conditions in cyclic voltammetry and the hydrodynamic conditions in HPLC detection frequently result, in the case of oxidations, in the optimum potential being shifted slightly to more positive values. Anderson et al. [7], have attempted to quantify the difference between the optimum potential for operation under hydrodynamic conditions and the peak and half-peak potentials obtained from cyclic voltammetry. Although this may have application where well-resolved cyclic voltammograms are obtained, in the authors experience many compounds that are less easily oxidized do not show well-resolved cyclic voltammograms at glassy carbon. (The method requires that the same electrode material... 

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