Static mercury drop

Mercury electrodes (a) hanging mercury drop electrode (b) dropping mercury electrode (c) static mercury drop electrode. 

A form of voltammetry using a dropping mercury electrode or a static mercury drop electrode. 

FIGURE 4-7 The static mercury drop electrode and its cell stand. 

QTA Quartz tube atomiser SDME Static mercury drop electrode... 

W. M. Peterson, "The Static Mercury Drop Electrode , Amer. Lab. Dec. (1979) 69 (available from EG G PARC as Note T-2). 

Fig. 5.10. PARC Model 384B polarographic analyzer and Model 303A static mercury drop electrode. 

The Model 303A static mercury drop electrode (SMDE) has received continuous design improvements (cf., Fig. 3.28 and associated explanation), e.g., the larger drop size afforded by the 303A design has yielded a further increase in sensitivity and the flip of a switch converts it into an extremely stable HMDE for stripping and/or square-wave voltammetry. ... 

Willie et al. [508] used Unear sweep voltammetry for the determination of molybdenum. The molybdenum was adsorbed as the Eriochrome Blue Black R complex on a static mercury drop electrode. The method was reported to have a limit of detection of 0.50 xg/l and the results agreed well with certified values for two reference seawater samples. 

Temperature effect on the electrodeposition of zinc on the static mercury drop electrode (SMDE) and glassy carbon (GG) electrode was studied in acetate solutions [44]. From the obtained kinetic parameters, the activation energies of Zn(II)/Zn(Hg) process were determined. 

Fraga etal. [71] have proposed a new stripping voltammetric method for the determination of titanium and Co(II) [72] based on the adsorptive accumulation of its hydroxynaphthol blue complex on a static mercury drop electrode. 

Through, for reasons of mathematical simplicity, planar electrodes are assumed in most voltammetric derivations, they are seldom used in practice because of the difficulties of their fabrication. The favorite, and most convenient, electrode of experimental voltammetrists is the static mercury drop. This spherical electrode cannot always be adequately approximated by a planar model. In particular, eqn. (139) does not hold for a spherical electrode and hence semi-integration cannot be used to generate accurate values of surface concentrations. Indeed, even eqn. (137) is invalid, the concentrations of O and R not being linearly related at the surface of a spherical electrode. 

Although normal pulse polarography was developed mainly for analytical purposes, it is a valuable and simple method to study kinetics of not-too-fast electrode reactions. As the other controlled potential techniques, it has the advantage of being applicable to systems where only one of the redox components is present initially. The technique is closely related to d.c. polarography [11] and the expressions discussed in this section are directly applicable to the case of d.c. polarography performed with the static mercury drop electrode (SMDE) if the correction for the spherical shape of this electrode is negligible [21, 22]. 

The following types of mercury electrodes have been widely used for voltammetry dropping mercury electrode (DME), hanging mercury drop electrode (HMDE), static mercury drop electrode (SMDE), streaming mercury electrode (SME), and mercury film electrode (MFE). We begin our discussion with a description of the construction and properties of the DME because this electrode has a long history and continues to be used for both analytical and fundamental studies. 

The static mercury drop electrode (SMDE) was first introduced commercially in the late 1970s by EG G Princeton Applied Research [27]. It utilizes a method of drop formation in which the mercury drop is dispensed rapidly and then allowed to hang stationary at the capillary tip. When used in a DME mode of operation, the drops can be repetitively formed and dislodged at desired time... 

Figure 14.8 The first commercial version of the static mercury drop electrode, the EG G Princeton Applied Research model 303A, in fully equipped cell stand.

Mercury is the electrode material of choice for many electrochemical reductions and some unique oxidations (see Chap. 14). We have explored the use of both small mercury pools and amalgamated gold disks in thin-layer amperometry. Other workers have used pools in a capillary tube [7] and amalgamated platinum wire [8]. In 1979, Princeton Applied Research introduced a unique approach based on their model 303 static mercury drop electrode (see Sec. II.F). Our laboratories and MacCrehan et al. [9] have focused on the use of amalgamated gold disks. This approach results in an inexpensive, easily prepared, and mechanically rigid electrode that can be used in conventional thin-layer cells (Sec. II.C) of the type manufactured by Bioanalytical Systems. 

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... 

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