Showing papers on "Supporting electrolyte published in 1983"

Polymer Films on Electrodes XI . Electrochemical Behavior of Polymer Electrodes Produced by Incorporation of Tetrathiafulvalenium in a Polyelectrolyte (Nafion) Matrix

Abstract: The electrochemical behavior of the cation exchange polymer Nafion containing tetrathiafulvalenium (TTF+) on a platinum substrate is described. The polymer electrode shows cyclic voltammetric behavior similar to that of solid films of TTF on platinum. In the oxidized form of the electroactive molecules in the polymer (TTF+) forms nonstoichiometric complexes with Br−. The peak potentials in cyclic voltammetry shift with changes in concentration of supporting electrolyte, temperature, and anion of the supporting electrolyte. Very narrow cyclic voltammetric waves are observed that result in part from attractive interactions between the electroactive molecules. The separation in peak potential of the reduction and oxidation waves is explained by formation of which stabilizes the oxidized form (TTF+) and makes it harder to reduce. Peak potentials for the oxidation and reduction shift closer together as the scan rate is lowered, which is explained by a "square (reaction) scheme."

Reversible sequential transfer of two electrons at the same potential in bis(1,3,5-triketonato)dicopper(II) complexes and their diamine Schiff bases. Effect of sodium(+) and similar ions on the cyclic voltammetry

Abstract: The cyclic voltammetry of four binuclear Cu(II) 1,3,5-triketonates and their diamine Schiff-base derivatives has been investigated in DMF with (C/sub 2/H/sub 5/)/sub 4/NClO/sub 4/ as the supporting electrolyte. Addition of simple cations such as Na/sup +/ to these solutions has a profound effect on the reduction potentials of the Cu(II) ions and on the stability of the reduced product. In the presence of a sufficient concentration of Na/sup +/ ions, the complexes exhibit one CV wave due to the coppers with peak separations of 42-44 mV and cathodic half-peak widths of 42-44 mV also. These results may be obtaned with no instrumental iR compensation, providing a high concentration of the supporting electrolyte is present. The process is reversible with use of the criteria of scan rate dependence of the cathodic peak current and width and the equivalence of the cathodic and anodic peak heights. Controlled-potential electrolysis results prove that the process involves the transfer of two electrons. All of the experimental facts may be explained by the reversible, sequential transfer of two electrons at the same potential. Although the two Cu(II) ions in the diamine Schiff bases are in much different coordination environments within the same molecule, they give risemore » to the same CV wave shapes as the triketonates; i,e., ..delta..E/sub p/ and E/sub pc/ - E/sub p///sub 2/ both are very nearly 42 mV. Thus, they also undergo two-electron transfer at the same potential. The only significant difference between the simpler binuclear Cu(II) triketonates and the diamine Schiff-base derivatives is that E/sub 1///sub 2/ values for the Schiff bases are about 0.1V more negative than for their triketonate analogues.« less

Electrochemical Studies on Minoxidil and Its Determination in Tablets by Differential-Pulse Polarography.

Abstract: A simple differential-pulse polarographic method has been developed for the determination of minoxidil in pharmaceutical dosage forms. The extracting solvent was methanol and the supporting electrolyte was 1.0 N sulphuric acid. An excellent linear relationship was obtained between the concentration and current peak height with a correlation coefficient of 0.9999. Good agreement was obtained between results with the differential-pulse polarography method and those by the manufacturer's method of assay. There was no interference by the tablet excipients. In acid solution, a mechanism for reduction at –1.2 V is proposed, which involves the transfer of four electrons as well as dehydration and deamination steps.

Coulometric determination of thiols and hydrazines with electrogenerated iodine in methanol in the presence of potassium acetate

Abstract: Conditions have been established for the quantitative electrochemical generation of iodine in methanol in the presence of potassium acetate. The conditional redox potentials of the iodine/iodide system in the same supporting electrolyte have been determined. With increasing concentration of potassium acetate in the solutions, the conditional redox potentials of the iodine/iodide couple were only negligibly decreased. In the presence of sodium perchlorate the redox potentials were noticeably increased. Anodically generated iodine has been applied to coulometric titration of thiols and hydrazines. The error of the determinations did not exceed ±2%.

Electrochemical Oxidation of Chlorpromazine Hydrochloride in Aqueous Buffer

Abstract: The electrochemical oxidation mechanism of chlorpromazine hydrochloride (CPZ-HCI) was examined in aqueous buffers in the pH range from 2 to 7 Three anodic waves were observed on the cyclic voltammogram of CPZ The peak potential of the second wave was highly dependent on the properties of the supporting electrolyte, but the first peak was independent of these properties At a higher pH or higher concentration of electrolyte, both peak currents increased The final oxidation product was found to be chlorpromazine sulfoxide by comparison of its ultraviolet (UV) absorption spectrum and Rf value of thin layer chromatography (TLC) with those of an authentic sample The experimental results suggest that the first wave is a catalytic wave and depends on the pH and the concentration of the supporting electrolyte, but that the second is an oxidation wave of CPZ-buffer anion adducts

Polarographic behaviour of uranium (VI) in organic solutions

Abstract: Polarographic determination of uranium (VI) has been studied in the organic extraction phase TBP—diluent along with a selected aprotic solvent (i. e. dimethyl sulfoxide or N,N-dimethylformamide). DMF was found more suitable because it dissolves the organic extraction phase better than DMSO. U (VI) extracted in TBP-kerosene, n-hexane, cyclohexane, n-dodecane, benzene, from nitric acid medium can be determined in an organic solution (e. g. 50% DMF-30% TBP-20% kerosene) where it gives a well defined wave. In the organic solution, nitric acid added and/or extracted from the aqueous phase was found as an excellent supporting electrolyte for uranium determination.

Production of polymer film

Abstract: PURPOSE: To obtain a homogeneous polymer film having stable physical properties in a good yield and to enable electrolytic oxidation to be carried out over a long period of time, by subjecting a reaction system contg. a specified compd., a supporting electrolyte and a solvent to electrolytic oxidation in an inert gas atmosphere. CONSTITUTION: A reaction system contg. a supporting electrolyte, a solvent and a compd. selected from among benzene or its derivatives (a), a five-membered heterocyclic compd. (b) contg. an element of the oxygen or nitrogen group and compds. (C) in which a plurality of rings selected from among a benzene ring and five-membered heterocyclic rings contg. an element of the oxygen or nitrogen group are bonded directly or through an ether, sulfide, selenide or telluride linkage to each other or one another, is subjected to electrolytic oxidation in an inert gas atmosphere to produce the film of the polymer of said compd. Hydrogen and at most two groups selected from among halogen, hydroxyl, amino and 8C or lower hydrocarbon groups are attached to the benzene ring or the five-membered heterocyclic ring of the above compds. COPYRIGHT: (C)1984,JPO&Japio

Describing the adsorption of potential determiningions on variable charge mineral surfaces

Abstract: A computer program was developed to elaborate the titration curves of amphoteric surfaces according to the double layer theory. The zpc, identified from the intersection point of the titration curves carried out at different ionic strengths, fell at pH 3.15, 9.45 and 7.65 for Si, AI and Fe hydroxides, respectively. The Stern model described quite satisfactorily the relation between σ 0 and ψ 0 . Some problem was presented by Si surfaces which were then treated by a different calculation procedure. The δ values, the Stern layer thickness, were very high for the SI surfaces and increased with decreasing ionic strength. A different behaviour was showed by AI and Fe hydroxides; in these cases δ values were very low and increased with increasing electrolyte concentration. These results were discussed in terms of surface structures and activity of the supporting electrolyte.