Showing papers on "Supporting electrolyte published in 1972"

Binding of calcium to serum albumin. III. Influence of ionic strength and ionic medium.

Abstract: A marked inverse relation between calcium binding to serum albumin and ionic strength has been demonstrated by means of an ultrafiltration method and shown to be identical in NaCl and KCI medium, while magnesium binds competitively to albumin with the same affinity as calcium ions. The ionic strength dependence has been resolved into a linear relation between log calcium ion activity coefficient and log apparent intrinsic association constant, whose extrapolated value at zero ionic strength of supporting electrolyte is 1445±67 litres/mole. The importance of constant ionic strength in binding studies is emphasized.

Polarographic Investigation of Alkali Metal Ions in Hexamethylphosphoramide

Abstract: The polarographic behavior of alkali metal ions in hexamethylphosphoramide (HMPA) has been found to be greatly influenced by the cations of the supporting electrolytes. With 0.05 M Et4NClO4 as the supporting electrolyte, cesium and rubidium ions give diffusion-controlled, reversible waves at−2.32 and −2.35 V, respectively, vs. the Ag/0.1 M AgClO4 electrode, but sodium and lithium ions are not reduced until the reduction of the supporting electrolyte (−3.1 V). The potassium ion gives a wave at −2.37 V with a limiting current controlled by the rate of the preceding process. In 0.05 M Bu4NClO4 solutions, the reduction wave of the potassium ion is diffusion-controlled, but that of the sodium ion is kinetic and is very small. The lithium ion is not reduced until −3.1 V. In 0.05 M LiClO4, even the sodium ion is reduced reversibly with E1⁄2 at −2.47 V, while the reduction of the lithium ion starts from −2.65 V. In mixed supporting electrolytes, the presence of the tetraethylammonium ion is the determining factor...

Study of Hydration and Association of Ions in Solution. II. Complete Resolution of Tris(ethylenediamine)Cobalt(III), Chromium(III), and Rhodium(III) Complexes by Means of Paper Electrophoresis

Abstract: Complete resolution of racemic [M en3]3+ (M=CoIII, CrIII, and RhIII) by means of electrophoresis was achieved in a background solution of sodium d-tartrate and aluminum chloride. Electrophoretic data obtained under various conditions (various compositions, concentrations, and pH values of supporting electrolyte solutions) indicated that the separation of the enantiomers of [M en3]3+ complexes was accomplished not by the d-tartrate anion but by some aluminum d-tartrate complex anion.

Proton Mobility in Water in Glass Pores of 15 µm Diameter

Abstract: OUR work on hydrogen ion mobility1–4 led us to compare values of diffusion coefficients measured by polarography and by porous diaphragm cells. When D/D° (D = diffusion coefficient of an ion in a supporting electrolyte solution, D° = diffusion coefficient at infinite dilution, calculated from the Nernst equation) was plotted against concentration of supporting electrolyte, the curves for metallic cations4 approached a D/D° value of 1 at infinite dilution. Our curves for the hydrogen ion in alkali halides also approached 1 but those obtained by Woolf5 using porous diaphragm cells approached a lower value.

Polarographic Behavior of Nickel(II) in Propionitrile and Benzonitrile in the Presence of Thiocyanate Ions

Abstract: The effect of the cation of the supporting electrolyte on the electrode reaction of nickel(II) in propionitrile and benzonitrile solutions containing thiocyanate ion was investigated by DC polarography and i-t curve analysis. In the absence of thiocyanate ion, a propionitrile solution of nickel(II) gives a single irreversible wave in LiClO4 and NaClO4 supporting electrolytes and a double wave in Et4NClO4 and n-Bu4NClO4, and a benzonitrile solution of nickel(II) gives a double wave in alkali metal and quaternary ammonium perchlorates. Nickel(II) in these nitrile solvents in the presence of thiocyanate ion exhibits a catalytic pre-wave in alkali metal perchlorates and a catalytic maximum wave in quaternary ammonium perchlorates. The double wave of nickel(II) in the absence of thiocyanate ion is due to the inhibition of the charge transfer process by the relatively weak adsorption of quaternary ammonium cations and not to the presence of two electroactive species. A mechanism which involves the cyclic regene...

Effect of irradiation on electrode processes. Part 1.—The hydrogen electrode in dilute solutions

Abstract: The effect of 60Co-γ and 1 MeV electron irradiation on the kinetics of the H2—H+ exchange on platinum electrodes immersed in hydrogen-saturated dilute aqueous solutions (pH 1.04 to 3.9; no supporting electrolyte) was studied. The investigation was possible since the dissolved hydrogen facilitated the efficient radical chain decomposition of the electrochemically-active radiolytic hydrogen peroxide. Two principal radiation effects were observed: (i) exchange current densities were increased by amounts which were too large to be explained by the catalytic activity of the unstable intermediates. It was therefore proposed that radiation generates electrochemically active sites by the displacement of surface metal atoms. (ii) irradiation led to small negative shifts in the rest potential, the magnitudes of which were proportional to the dose rate and to the electrode polarization resistance. The shifts were either a consequence of the fact that irradiation accelerates anodic more than cathodic processes; or were due to the establishment of mixed potentials involving the H2—H+ exchange (E0= 0.0 V) and the oxidation of radiolytic hydrogen atoms (E0=–2.1 V). Quantitative results favoured the former explanation.

Square-wave polarographic determination of traces of copper in water

Abstract: A square-wave polarograph [3] has been used to determine trace amounts of copper in potable water and in Iowa River water By using a combination of sodium chloride (10 M) and perchloric acid (007 M) as a supporting electrolyte under acidic conditions (pH<1), 2 ppb copper could be determined in the samples without and with preconcentration Copper in the samples was determined with reproducibility of ± 013 ppb and so this technique is more reliable than a more used determination of complex salts by atomic absorptionspectrophotometry

溶媒抽出ポーラログラフ法による水銀(ii)の定量

Abstract: The application of polarogphic method to the CHCl3-extract of the ternary complex composed of Hg(II), Cl- and pyridine(py) is studied. Mercury(II) reacts with chloride ion in the presence of pyridine and forms the ternary complex HgCl2py2. The complex is extractable into chloroform in the pH range from 5.5 to 6.5. The ternary complex can be reduced at the dropping mercury electrode and the reduction wave is applied to the determination of mercury(II). At first, mercury(II) is extracted into chlorofrom as the ternary complex HgCl2py2. The 6 N HNO3, the most suitable supporting electrolyte solution, and methylcellosolve, the mixing solvent, are added to the chloroform extract. This ternary mixture is employed as the polaro- graphic electrolyte solvent. In the AC polarographic method, it is unnecessary to purge dissolved oxygen. The reduction of the ternary complex HgCl2py2 may be considered to proceed in one step involving the addition of two electrons, as shown by HgCl2py2 + 2e- Hg↓ + 2Cl- + 2 py The half-wave potential of this wave is about +0.18 V vs. SCE. The plot of log{i2/(ia-i)} against potential E is linear and has a slope of 30 mV at 20°C. The limiting current id is proportional to the root of the height of the mercury column. Consequently, the electrode reaction is reversible and diffusion-controlled. The relative temperature coefficient of id is 1.44% deg-1 at 20°C. The available range of the present method covers from 0.2 mg (5 x 10-5 mol/l) to 1 mg (3 X 10-4 mol/l) of mercury (II) in 20 ml of sample water and the time required for a single deter-mination is about 30 min. Cu2+, small amounts of Fe2+ and Fe3+ do not interfere, but I-, Br- and SCN- interfere.

Electrolytic reduction and cleavage of cyclohexane-1,4-dione

Abstract: The reduction of cyclohexane-1,4-dione (1), hexane-1,4-dione (2), and cyclohexanone on a mercury electrode have been investigated. Water and propan-2-ol–water (4 :1) were used as the solvents and tetraethylammonium toluene-p-sulphonate was the supporting electrolyte. Current–potential curves have been measured and preparative electrolyses have been performed. Only compound (1) reacted [up to –2·3 V(SCE)] and yielded the following products: 1,1′-dihydroxybicyclohexyl-4,4′-dione (3), hexane-2,5-dione (2), 4-hydroxycyclohexanone (4), and cis- and trans-1,4-cyclohexanediol [(5) and (6)]. At all potentials the yield of cis-compound (5) exceeded that of trans-compound (6). The ratio cis(5):trans(6) decreased with increasing cathodic potential. Possible mechanistic paths leading to the different products and adsorption phenomena involved in their formation are discussed.

Polarographic study of Iron (III)-Resacetophenoneoxime complex

Abstract: The polarographic behaviour of Iron (III)—Resacetophenoneoxime complex at pH 5.8 in a supporting electrolyte of 0.1 M sodium per-chlorate was studied. The results indicated a diffusion controlled irreversible reduction of the complex. The composition of the complex corresponded to the ratio metal to oxime as 1: 1. The stability constant of the complex was 2.78 × 10−5.

Electrochemical Oxidation of Polymer Anions and Arene Anions

Abstract: In order to investigate the reactivity of carbanions in anionic polymerizations, oscillopolarographic measurements of oxidation potentials of polymer anions and arene anions were carried out in tetrahydrofuran solutions with sodium tetraethyl-aluminate as a supporting electrolyte. The oxidation potentials of the carbanions measured with a microplatinum electrode were expressed against the standard potential of naphthalene radical anion: phenanthrene−, 0 V; biphenyl−, 0 V; anthracene2−, 0.27 V; stilbene2−, 0.48 V; (polystyrene)2−, 1.26 V; [poly(α-methylstyrene)]2−, 1.13 V; (diphenyl-ethylene2)2−, 1.13 V, poly(4-vinylpyridine)2−, 1.75 V, fluorene−, 1.71V. There is a linear relationship between oxidation potentials and energy level of the highest occupied molecular orbitals of these carbanions, which were obtained from the Huckel molecular-orbital method. It was suggested that the oxidation wave was caused by direct electron transfer from carbanion to anode. The carbanion, which was reported to have a high reactivity for the initiation or propagation of anionic polymerization, exhibited a less noble oxidation potential. The electrolytic oxidation of disodium α-methylstyrene tetramer yielded an oligomer of high molecular weight, 1000, in anodic compartment. For the anodic reaction, it is proposed that one electron transfer forms radical species followed by radical coupling.

Polarographic reduction of D-glucurono-γ-lactone in nonaqueous media

Abstract: The nonaqueous polarographic reduction of D-glucurono-γ-lactone in dimethylformamide using tetrabutylammonium iodide as the supporting electrolyte (apparent E1/2=− 1.94 V versus mercury pool) is analytically applicable over the concentration range of 50–300μg/ml.