Dropping Hg electrode

To overcome some of the problems associated with aqueous media, non-aqueous systems with cadmium salt and elemental sulfur dissolved in solvents such as DMSO, DMF, and ethylene glycol have been used, following the method of Baranski and Fawcett [48-50], The study of CdS electrodeposition on Hg and Pt electrodes in DMSO solutions using cyclic voltammetry (at stationary electrodes) and pulse polarography (at dropping Hg electrodes) provided evidence that during deposition sulfur is chemisorbed at these electrodes and that formation of at least a monolayer of metal sulfide is probable. Formation of the initial layer of CdS involved reaction of Cd(II) ions with the chemisorbed sulfur or with a pre-existing layer of metal sulfide. 

It is not generally acknowledged that, at about the same time, Kolthoff and Miller [25] also described reactions occurring at the dropping Hg electrode that exhibited current-potential curves in reaction mixtures that yielded mixed potentials, a term they also employed. 

Determined by polarography with the dropping Hg electrode in 0.09 N KC1 in 57% alcohol. 

The simple linear-sweep voltammetry (LSV) or linear potential sweep chronoamperometry (of which polarography with a dropping Hg electrode is the earliest example) can be understood simply if one looks at just the first rise to a peak in Fig. 11.70. 

Current-potential relationships at the dropping Hg electrode (d.c. polarography) constitute the oldest voltammetric measurements. The advantages of the dropping-Hg electrode (dme) include a clean electrode surface undergoing constant and reproducible renewal and highly developed and well-tested polarographic theory. ... 

The elecrochemical reduction of l-hydroxymethyl-9,10-dimethoxy-4-cyclohexylimino-l,2,4,5,6,116-hexahydro[l,3]oxazino[4,3-fl]isoquinoline on a dropping Hg electrode was studied (87PHA858). 

Differential pulse polarography is used as part of a multielement procedure for the determination of Cr in foods. The sensitivity is described as 0.24 mg/kg Cr (Holak, 1983). Trace amounts of Cr have also been determined by using the catalytic current at a dropping Hg electrode (Sarawathi et al.. 1990). The determination of trace amounts of Cr(VI) and/or Cr lll) or total Cr by electrochemical methods are described by Pratt and Koch (1986), Boussemart and Van den Berg (1991), and Elleouet et al. (1992), to cite just these few. 

A dropping Hg-electrode usually serves as polarizable micro-electrode. Either an Hg bottom electrode, a calomel electrode or another electrode of the second type is used as non-polarizable reference electrode. 

A sensitive method for the estimation of different surface active compounds (tetraalkylammonium salts, dextrans, crude oil components) in water is based on the measurements of the depression of the electrocapillary curve under conditions where the transport of the compound to the dropping Hg-electrode is accelerated by stirring of the solution being examined[12] The detection limit is in the range of 10-100 jjg 1 More details on "adsorptive polarographic analysis" are given in[13]. 

Electrochemical reductions have been referred to as compulsory ET processes, and for inert smooth Pt and some C, electrodes are assumed to be outer-sphere ET. For a dropping Hg electrode, which is the case considered here, the situation has been discussed Ref. 194, p 79. 

Iron and copper chelate solutions were analyzed by using DC poiarography (dropping Hg electrodes), using the classical methods of Kohithoff. ... 

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