Copper chromium oxide electrodes

Electrochemical detection of carbohydrates at nickel-copper and nickel-chromium-iron alloy electrodes has been reported for sorbitol, and has been used as a detector for HPLC analysis [36]. Oxidation of various carbohydrates at the electrodes was used for detection, and baseline separation was achieved for mixtures of sorbitol, rhamnose, glucose, arabinose, and lactose. 

Copper(II) and cerium(IV) have been studied as oxidants in acetonitrile. The copper(II)-copper(I) couple has an estimated electrode potential of 0.68 V relative to the silver reference electrode. It has been studied as an oxidant for substances such as iodide, hydroquinone, thiourea, potassium ethyl xanthate, diphenylbenzidine, and ferrocene. Cerium(IV) reactions are catalyzed by acetate ion. Copper(I) is a suitable reductant for chromium(VI), vanadium(V), cerium(IV), and manganese(VII) in the presence of iron(III). For details on many studies of redox reactions in nonaqueous solvents, the reader is referred to the summary by Kratochvil. ... 

Electrolytic oxidation of anthracene in 20 per cent sulfuric acid solution with 1 per cent of vanadium pentoxide present is carried out at 80° C. with lead electrodes and a current density of 300 amperes per square meter at 1.6 volts. Good yields have been claimed 10 for this process. Air under pressure has been used for the oxidation of anthracene in the form of dispersions in aqueous ferric sulfate solutions,20 or as a solution iu pyridine or dispersion in aqueous alkaline solutions preferably in the presence of catalysts 21 of copper, cobalt, nickel or lead compounds. Vanadium compounds have been found more active than chromium compounds for use as oxidation catalysts in the form of suspensions in the liquid phase, as in the preparation of aniline black.22 Anthracene suspended in water or dilute sulfuric arid or dissolved in a solvent as acetone is oxidized with ozone, or ozonized oxygen at ordinary temperatures.28... 

Zagal, J.H., S. Lira, and S. Ureta-Zanartu (1986). A mechanistic study of the electro-oxidation of hydrazine on phthalocyanines of vanadyl, chromium, manganese, nickel, copper and zinc attached to graphite electrodes. J. Electroanal. Chem. 210(1), 95-110. 

Electrode systems of the first kind are not widely used for potentiometric analyses for several reasons. For one, they are not very selective and respond not only to their own cations but also to other more easily reduced cations. For example, a copper electrode cannot be used for the determination of copper(Il) ions in the presence of silver(l) ions, which are also reduced at the copper surface. In addition, many metal electrodes, such as zinc and cadmium, can be used only in neutral or basic solutions because they dissolve in the presence of acids. Third, some metals are so easily oxidized that their use is restricted to solutions that have been deaerated. Finally, certain harder metals — such as iron, chromium, cobalt, and nickel — do not provide reproducible potentials. Moreover, for these electrodes, plots of pX versus activity yield slopes that differ significantly and irregularly from the theoretical (-O.O592//1). For these reasons, the only electrode systems of the first kind that have been u,sed are Ag-Ag and Hg-Hg2 in neutral solutions, and CuCu Zn-Zn Cd-Cd , Bi-Bi= Tl-TI, and Pb-Pb in deaerated solutions. 

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