Current maximum suppresser

Figure 6.7 Polarogram of air-saturated water, i.e. a polarogram of oxygen. The solution also contains KNO3 as an inert ionic electrolyte (0.1 mol dm ) and Triton X-100 (a non-ionic surfactant) as a current maximum suppresser (see Section 6.8.1). From Bard, A.J. and Faulkner, L.R., Electrochemical Methods Fundamentals and Applications, Wiley, 1980. Reprinted by permission of John Wiley Sons, Inc.

The magnitudes of these maxima can be decreased almost completely by adding a surfactant to the analyte solution - we call such an additive a current maximum suppresser (or, sometimes, a depolarizer). The usual suppresser employed is Triton X-1(X) (a non-ionic surfactant (detergent)), which is added to the solutions at concentrations of no more than 0.(X)2 mol dm. ... 

Current maximum suppresser A chemical, usually a surfactant (detergent), added to polarography solutions in order to decrease the incidence of polaro-graphic peaks (see Section 6.8.1). 

After measuring the zero profile, AU measurements are carried out with the injection of a cathodic protection current. In contrast to the zero profile measurements, the distance between the individual measurements is 25 to 50 m. Shorter distances between the measuring points are used only at depths where there are unusual AU profiles. Current should be injected at at least three different levels. The protection current density of about 12 mA m obtained from experience should be the basis for determining the maximum required protection current. As shown by the results in Fig. 18-3, the AU profiles are greater with increasing protection current. The action of local cells is suppressed when the AU values no longer decrease in the direction of the well head. This is the case in Fig. 18-3 with a protection current I = 4A. 

Formaldehyde Oxidation The faradaic current for formaldehyde oxidation (solid line in Fig. 13.6a) is largely suppressed during the first minute after stepping to 0.6 V, and then increases with time, resulting in an S-shaped transient. It reaches its maximum current about 4-5 minutes after the potential step, followed by a slow and nearly linear decay of the faradaic current with time (solid line in Fig. 13.6a). In comparison with formic acid oxidation (solid line in Fig. 13.5a), three major differences can be noted ... 

In a few instances, the polarographic wave is accompanied by a large peak (where the current rises to a maximum before returning to the expected diffusion current plateau). Such an undesired peak, known as the polarographic maximum, is attributed to a hydrodynamic flow of the solution around the expanding mercury drop, can be suppressed by adding a small amount of a surface-active material (such as Triton X-100). 

Of the diarylarsinic acids only the unsubstituted diphenylarsinic acid has been studied in detail by polarography in buffered aqueous solution" . The reduction is associated with adsorption as indicated by a prewave and a polarographic maximum on the main wave which, however, could be suppressed by addition of Triton X-100" . The height of the reduction wave is directly proportional to the concentration of Ph2 AsO(OH) in the range lO -lQ- M, and the limiting current (ij) is almost entirely diffusion-controlled". Similar conclusions were drawn for a series of bis(aminophenyl)arsinic acids based on measurements of ij as a function of the concentration and the height of the mercury column ... 

Lee and Hwang synthesized a PF with aryl side chains 6 via the Yamamoto coupling reaction [20]. The device fabricated therewith (ITO/PEDOT PSS/6/ Ca/Al) emits blue light with suppressed long tail emission but gives low performance with maximum efficiency of 0.03 cd A-1 and maximum luminance of 820 cd nr2. Note that the device could bear considerably high current density (>1.5 A cm-2). 

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