Electrodes silver amalgam

The potentiometric micro detection of all aminophenol isomers can be done by titration in two-phase chloroform-water medium (100), or by reaction with iodates or periodates, and the back-titration of excess unreacted compound using a silver amalgam and SCE electrode combination (101). Microamounts of 2-aminophenol can be detected by potentiometric titration with cupric ions using a copper-ion-selective electrode the 3- and... 

The - electrochemical window of polished solid silver amalgam electrode (p-AgSAE) as for an electrode which does not contain liquid mercury is exceptionally broad. This fact allows the application of p-MeSAE for determination of species at rather negative potentials. An important advantage is that the electrodes from solid amalgams of different metals can be prepared in a relatively simple way, and that in their applications specific interactions between these metals and the studied compounds can be utilized. 

The solution to the right of the glass electrode is usually a buffer solution of KH2P04 and Na2HP04, with 0.1 mol dm"3 of NaCl. The reference electrode is usually a calomel electrode, silver/silver chloride electrode, or a thallium amalgam/thallous chloride electrode. The emf of this cell depends on a(H + ) in the solution X in the same way as that of the cell with the Pt H2 electrode, and thus the same procedure is followed. 

Fig.4. Nitrobenzene anion radical formation at —0.4 V under potentio-static control at the silver amalgam electrode. The points at the curves indicate the start and the end resp. of the potential step. 

Strides and Kolthofif using DC polarography found that between pH 1 and pH 10.5 and at ca -0.25 V vj SCE, Reaction 5.2 also applied to GSH. Mairesse-Ducarmois et showed that following the oxidation of GSH, the product, GSHg, was adsorbed onto the mercury surface. Similar results have been observed with silver electrodes. Gold amalgam electrodes can also be used (see below). 

Bas, B., Jakubowska, M., and Gorski, L., 2011. Application of renewable silver amalgam annular band electrode to voltammetric determination of vitamins C, B1 and B2. Talanta. 84 1032-1037. 

Flow setup used for the potentiometric detection of cyanides. EC electrochemical cell containing two similar silver amalgam electrodes HC holding coil SV selection valve. 

Recipe for a silver amalgam electrode polish the Ag wire electrode (ca. 1 mm diameter) with fine alumonum oxide powder. Reduce at —1.0 V(vs. SCE) for 3 minutes ih a cell containing nitric acid (pH 1.5) and a drop of mercury. While still holding the potential, touch the electrode surface to the Hg drop. Rinse several times with deionized water immerse in deionized water for 50 minutes. Polish with aluminum oxide powder and rinse again. The electrode can be used or months, like any other solid electrode. 

A working electrode that gives facile charge transfer is essential in the characterization of the electrochemical properties of a system by simulation and fitting analysis. Methylcobalamin usually shows adsorption on common electrode materials. After an exhaustive examination of electrode materials, it was found that a silver amalgam electrode gives the best electrode response. 

Figure 6-2 Double potential step chronoamperometry experiment and fitting result of methylcobalamin in mixed solvent (40% DMF, 60% methanol) at — 30°C. Silver amalgam electrode, 0.25 mm in diameter, methylcobalamin = 1 mM, TBAF = 0.30 M. (a) Result fitted by kchem = 590s solid points are experimental results, (b) Detail of the fitting with error range, where the data close to noise background (at the end of the time period) are ignored open points are experimental results. Curve a with = 590 s b with 690s" and c with 490s"V (Adapted from Reference 3.)...

Figure 6-3 Cyclic voltammograms of 2.0 mM methylcobalamin in a mixed solvent (40% DMF, 60% methanol) at — 30°C. The s porting electrolyte is TBAF in 0.30 M, and the working electrode is a silver amalgam electrode, 1.6 mm in diameter. The simulation/fitting results of parameter are shown in Table 6-1. Lines represent experimental data, and dots indicate the simulation/fitting results. Scan rates (mV/s) (a) 50, (b) 100, and (c) 300. (Adapted from Reference 3.)...

Instead of pure mercury less toxic solid silver amalgam has been also proposed for construction of calomel electrodes [109, 110]. Long-term as well as shOTt-time test confirms the potential of the new electrode equal to that of classical calomel electrode within the limits of 1 mV. This electrode was also found to be nonpolarized in the presence of current below 2 mA. 

Mercury meniscus modified solid amalgam electrodes of silver and of copper proved experimentally by Yosypchuk et al. [40] as acceptable substitutes for the hanging mercury drop electrode (HMDE) in highly sensitive cathodic stripping voltammetric analyses of adenine and guanine, and of DNA after acid-treatment.The analyses are best done in weakly alkaline solutions and in the case of silver amalgam electrode copper (11) ions can be added to the solution. With both electrodes using the differential pulse or the direct current voltammetry, the substances can be determined in the nanomolar level. Also, their surfaces can be simply reactivated electrochemically. 

Kapturski P, Bobrowski A (2007) Silver amalgam film electrode of prolonged application in stripping chronopotentiometry. Electroanalysis 19 1863—1868... 

Strasunske K, Mikkelsen 0, Billon G (2010) Nafion coated silver amalgam electrode for determination of trace metals by anodic stripping voltammetry. Electroanalysis 22 501-507... 

Piech R (2013) Sensitive voltammetric determination of titanium(IV) in catalytic adsorptive mandelic acid-chlorate(V) system on renewable silver amalgam film electrode. Electroanalysis 25(3) 716-722... 

Guzsvany V, Petrovic J, Krstic J, Papp Z, Putek M, Bjelica L, Bobrowski A, Abramovic B (2013) Renewable silver-amalgam film electrode for voltammetric monitoring of solar photodegradation of imidacloprid in the presence of Fe/Ti02 and Ti02 catalysts. J Electroanal Chem 699 33-39... 

Guziejewsk D, Brycht M, Skrzypek S, Nosal-Wiercinska A, Ciesielski W (2012) Voltammetric determination of acibenzolar-s-methyl using a renewable silver amalgam film electrode. Electroanalysis 24(12) 2303-2308... 

Putek M, Guzsvany V, Tasic B, Zarebski J, Bobrowski A (2012) Renewable silver-amalgam film electrode for rapid square-wave voltammetric determination of thiamethoxam insecticide in selected samples. Electroanalysis 24(12) 2258-2266... 

Bas B, Bas S (2010) Rapidly renewable silver amalgam annular band electrode for voltammetry and polarography. Electrochem Common 12(6) 816-819... 

Piech R, Bas B, Niewiara E, Kubiak WW (2008) Renewable copper and silver amalgam film electrodes of prolonged application for the determination of elemental sulfur using stripping voltammetry. Electroanalysis 20(7) 809-815... 

Electrodes BDDE boron-doped diamond electrode, BiFE bismuth film electrode, CFiE carbon fibre electrode, CPE carbon paste electrode, GCE glassy carbon electrode, HMDE hanging mercury drop electrode, Hg(Ag)FE silver-amalgam film electrode, (M)CPE (modified) carbon paste electrode, MFE mercury film electrode, MWCNTs-Na/Bi multiwall carbon nanotubes dispersed in Nafion used in combination with Bi, SCE saturated calomel electrode, SMDE static mercury drop electrode, SP-BiFE screen-printed... 

Kapturski P, Bobrowski A (2008) The silver amalgam fihn electrode in catalytic adsorptive stripping voltammetric determination of cobalt and nickel. J Electroanal Chem 617 1-6... 

Bobrowski A, Gawlicki M, Kapturski P, Mirceski V, Spasovski F, Zarebski J (2009) The silver amalgam film electrode in adsorptive stripping voltammetric determination of palla-dium(ll) as its dimethyldioxime complex. Electroanalysis 21 36-40... 

Niaz A, Fischer J, Barek J et al (2(X)9) Voltammetric determination of 4-rtitrophenol using novel type of silver amalgam paste electrode. Electroanalysis 21 1786-1791... 

Reference Electrodes and Liquid Junctions. The electrical cincuit of the pH ceU is completed through a salt bridge that usually consists of a concentrated solution of potassium chloride [7447-40-7]. The solution makes contact at one end with the test solution and at the other with a reference electrode of constant potential. The Hquid junction is formed at the area of contact between the salt bridge and the test solution. The mercury—mercurous chloride electrode, the calomel electrode, provides a highly reproducible potential in the potassium chloride bridge solution and is the most widely used reference electrode. However, mercurous chloride is converted readily into mercuric ion and mercury when in contact with concentrated potassium chloride solutions above 80°C. This disproportionation reaction causes an unstable potential with calomel electrodes. Therefore, the silver—silver chloride electrode and the thallium amalgam—thallous chloride electrode often are preferred for measurements above 80°C. However, because silver chloride is relatively soluble in concentrated solutions of potassium chloride, the solution in the electrode chamber must be saturated with silver chloride. 

Electrodes and Galvanic Cells. The Silver-Silver Chloride Electrode. The Hydrogen Electrode. Half-cells Containing an Amalgam, Electrode. Two Cells Placed Back to Back. Cells Containing Equimolal Solutions. The Alkali Chlorides as Solutes. HC1 in Methanol or Ethanol Containing a Trace of Water. The Alkali Chlorides in Methanol-Water Mixtures. The Heal of Solution of HC1. Proton Transfer Equilibrium from Measurements of E.M.F. 

In the experiments to be described, in each case the half-cell was coupled to a Ag/AgOl half-cell, which in each case formed the positive electrode of the cell that is to say, on closing the external circuit, electrons flowed in the external circuit from the amalgam electrode to the silver electrode. This was the situation whether the solvent was water, or methanol, or a mixture of methanol and water. 

The silver reductor has a relatively low reduction potential (the Ag/AgCl electrode potential in 1M hydrochloric acid is 0.2245 volt), and consequently it is not able to effect many of the reductions which can be made with amalgamated zinc. The silver reductor is preferably used with hydrochloric acid solutions, and this is frequently an advantage. The various reductions which can be effected with the silver and the amalgamated zinc reductors are summarised in Table 10.11. ... 

Reductant equivalent weights of, 847 Reduction 409 by chromium(II) salts, 409 by hydrogen sulphide, 416 by Jones reductor (zinc amalgam), 410 by liquid amalgams, 412 by silver reductor, 414 by sulphurous acid, 416 by tin(II) chloride, 415 by titanium(II[), 410 by vanadium(II), 410 see also Iron(III), reduction of Reduction potentials 66 Reference electrodes potentials, (T) 554 Relative atomic masses (T) 819 Relative error 134 mean deviation, 134... 

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