Pulsed electrode

ECD for Use with Pulsed Electrode Potential ECD for Use with Constant Electrode Potential... 

Figure 12.18 Diagrams of two types of ECDs (a) ECD for use with pulsed electrode potential and (b) ECD for use with constant electrode potential. (From Cazes, J., Encyclopedia of Chromatography, Marcel Dekker Inc., New York, 2001. Used with permission.)...

Pulsed electrode heating till now did not find very broad application. The following examples mark the beginning of a research direction where heated... 

The source designs described so far are used in combination with a (triple) quadrupole instrument. Modifications of this design are required in the coupling to other types of mass analysers, e.g. the implementation of a gate or ion pulse electrode for use in combination with ion-trap and time-of-flight mass analysers. 

Sb can be shaped into NW by a number of approaches, e.g., pulsed electrode-position, patterning of nanoparticles, microwave-induced formation, and by using focused ion beams (FIB). For developing nanowires of Sb for pH measurements, the FIB technology was used. The material was exposed to a Ga" ion beam under high vacuum at room temperature. This procedure led to the formation of tangled Sb rods which formed a porous network of NW. 

Stripping voltammetry involves the pre-concentration of the analyte species at the electrode surface prior to the voltannnetric scan. The pre-concentration step is carried out under fixed potential control for a predetennined time, where the species of interest is accumulated at the surface of the working electrode at a rate dependent on the applied potential. The detemiination step leads to a current peak, the height and area of which is proportional to the concentration of the accumulated species and hence to the concentration in the bulk solution. The stripping step can involve a variety of potential wavefomis, from linear-potential scan to differential pulse or square-wave scan. Different types of stripping voltaimnetries exist, all of which coimnonly use mercury electrodes (dropping mercury electrodes (DMEs) or mercury film electrodes) [7, 17]. 

Osteryoung J and Murphy M M 1991 Normal and reverse pulse voltammetry at small electrodes Microelectrodes Theory and Applications (Nate ASI Series E vol 197) ed M I Montenegro, M A Queiros and J L Daschbach (Dordrecht Kluwer)... 

In hydrodynamic voltammetry current is measured as a function of the potential applied to a solid working electrode. The same potential profiles used for polarography, such as a linear scan or a differential pulse, are used in hydrodynamic voltammetry. The resulting voltammograms are identical to those for polarography, except for the lack of current oscillations resulting from the growth of the mercury drops. Because hydrodynamic voltammetry is not limited to Hg electrodes, it is useful for the analysis of analytes that are reduced or oxidized at more positive potentials. 

In hydrodynamic voltammetry the solution is stirred either by using a magnetic stir bar or by rotating the electrode. Because the solution is stirred, a dropping mercury electrode cannot be used and is replaced with a solid electrode. Both linear potential scans or potential pulses can be applied. 

In stripping voltammetry the analyte is first deposited on the electrode, usually as the result of an oxidation or reduction reaction. The potential is then scanned, either linearly or by using potential pulses, in a direction that removes the analyte by a reduction or oxidation reaction. 

---