Advantages over dropping-mercury electrode

What are two advantages of the dropping mercury electrode over a stationary electrode ... 

Polarography is based on the use of a dropping mercury electrode which consists of mercury in the form of small droplets issuing from the end of a fine-bore capillary. Despite the obvious slight practical complication of working with a dynamic rather than a static electrode, mercury in this form shows a number of distinct advantages over almost all other forms ... 

When the electrode does not have macrometric dimensions (i.e., for a radius smaller than 0.05 cm for a time of experiment of 1 s), the geometry becomes fundamental. In this section, special detail will be paid to spherical geometry. The use of spherical electrodes such that the Static Mercury Drop Electrode (SMDE) offers important advantages over solid electrodes on account of its smooth and... 

It is also possible to employ detectors with solutions flowing over a static mercury drop electrode or a carbon fiber microelectrode, or to use flow-through electrodes, with the electrode simply an open tube or porous matrix. The latter can offer complete electrolysis, namely, coulometric detection. The extremely small dimensions of ultramicroelectrodes (discussed in Section 4.5.4) offer the advantages of flow-rate independence (and hence a low noise level) and operation in nonconductive mobile phases (such as those of normal-phase chromatography or supercritical fluid chromatography). 

When mercury is used as the electrode material, detection is possible over a particularly wide cathodic potential range. The anodic range, however. is limited. It is thus commonly used for the detection of reducible species. Detectors which utilize a static mercury drop are particularly attractive as the dntp (working electrode) is easily renewed for each chromatogram this is quite an advantage for the reproducibility of response [42]. The construction and operation of detectors based on mercury drop electrodes have been reviewed [42], [43]. 

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