Kemula electrode

HMDE (hanging mercury drop electrode) Kemula electrode... 

Electrodes. The Hanging Mercury Drop Electrode is traditionally associated with the technique of stripping voltammetry and its capabilities were investigated by Kemula and Kublik.51 In view of the importance of drop size it is essential to be able to set up exactly reproducible drops, and this can be done as explained in Section 16.8 for the S.M.D.E. 

Astheimer and Schwochau have applied the voltametry method to the determination of low technetium concentrations in the presence of molybdate and perrhenate ions. Using a Kemula electrode technetium is concentrated on a mercury drop from alkaline solution of 6.0 x 10 M KTcO by electrolysis at a potential of — 1.0 V vs. SCE. Anodic stripping in 1 M NaOH yields a characteristic stripping curve (Fig. 14). The height of the peak at —0.33 V is proportional to the concentration of technetium in the range of 10 to 3 x 10 M. Technetium can be detected with an accuracy of +4%. The determination of 0.5 ng of technetium in a 10 fold molar excess of ReO or MoO is possible. 

Using the HMDE covered by calomel, Kemula and coworkers studied the oxidation of several other substances [67]. Kublik studied the oxidation of various ions at the HMDE covered by a film of HgO [68]. These electrodes may be used at even more positive potentials than platinum electrodes in the same solutions. Although the mechanism of oxidation at these electrodes is very interesting, platinum and carbon electrodes are more useful in practical work since their properties and stability are not as dependent on the nature of the sample. When using such electrodes at positive potentials, some current due to oxidation of mercury is inevitable. This limits the application of passivated mercury electrodes to rather concentrated sample solutions. 

While various dropping mercury electrodes (DMEs) have long been proposed as LC detectors, it is fair to say that they have never been put to significant practical use for this purpose. Kemula innovated this area in 1952 [16]. As the efficiency of LC columns improved, it became essential to reduce the volume... 

Another limitation of solid electrodes has been their complex diffusion-current response relative to time with slow-sweep voltammetry. The development of a capillary hanging-mercury-drop electrode (HMDE) by Kemula and Kublik,4,5 together with modem electronic instrumentation, allowed the principles of voltage-sweep voltammetry and cyclic voltammetry to be established. The success has been such that this has become one of the most important research tools for electrochemists concerned with the kinetics and mechanisms of electrochemical processes. These important contributions by Nicholson and Shain6 7 rely, as have all electrochemical kinetic developments, on the pioneering work by Eyring et al.8... 

From a historical viewpoint, it should be noted that LCEC was developed in a number of different configurationsasearly as the 19S0s(Kemula, 1952). None of these was successfully adopted for widespread use. The use of dropping mercury electrodes in many designs made them inconvenient for biomedical research. It may be frirly stated that nearly all developments were solutions in search of a problem. 

W. KEMULA (1902-1985) introduces polarographic detection in liquid chromatography (so-called chromatopolarography) (1952) Roczn chem 26 281 1956-1959 W. KEMULA (1902-1985) and Z. KUBLIK (1922-2005) introduce the hanging mercury drop electrode (HMDE or Kemula electrode) and anodic stripping voltammetry (1956) Roczn chem 30 1005 (1958) Anal Chim Acta 18 104 (1959/60) J Electroanal Chem 1 123... 

Stepwise changes in potential at a dropping mercury electrode were first employed by Kemula in 1930 while doing postdoctoral work at Charles University. 

Kemula W (1931) Polarographic studies by means the mercury dropping electrode (Polish). Kosmos 55 333-367... 

In Prague Kemula became deeply fascinated by polarography and phenomena, which occurred during electrochemical reactions on mercury electrodes. As a result, his thesis presented in 1932 to receive the Doctor of Science degree (Habili-tation) was connected with polarography. Three years later, in 1935, Professor Kemula became the Head of the Department of the Physical Chemistry at the University in Lwow. 

Static assays of mercury electrodes include the pool electrode and the hanging mercury drop electrode (HMDE developed by Kemula ). With the latter a mercury drop is placed on the tip of a capillary by squeezing the metal out of the reservoir with a micrometer screw-controlled piston. 

Kemula W, Zawadowska J (1980) New model of the hanging mercury drop electrode and its application in aqueous and non-aqueous media. Fresenius Z Anal Chem 300 39-43... 

Kemula W, Kublik Z (1958) The hanging mercury drop electrode. Anal Chim Acta 18 104-108... 

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