Showing papers on "Polarography published in 1971"
88 citations
TL;DR: In this paper, the reduction and oxidation processes of uranium(VI, (V), (IV) and (III) in aqueous perchlorate solutions have been studied using the dropping mercury electrode, the hanging mercury drop electrode and the thin-layer technique.
50 citations
36 citations
30 citations
TL;DR: A rapid polarographic method for the determination of chlordiazepoxide in tablets is described, which shows that the drug is strongly adsorbed at the electrode, so that it can be determined in biological materials without prior separation.
30 citations
29 citations
29 citations
TL;DR: In this paper, the potential structures of four nitrogen-donor macrocyclic complexes are discussed in terms of their visible, infrared and e.s.r. spectra, as well as on the basis of data obtained from conventional polarography and cyclic voltammetry.
Abstract: Copper(II) complexes of the types Cu(CR)(ClO4)2-.H2O, [Cu(CR)X](ClO4).nH2O (where X = Cl, Br, I and n = 1; X = NCS, n = 0), [Cu(CRH)](ClO4)2.H2O and [Cu(CRH)X](ClO4) (where X = Cl, Br, I) have been prepared. The ligands CR and CRH are the related four nitrogen-donor macrocycles 2,12-dimethyl-3,7,11,17-tetraazabicyclo [11.3.1]heptadeca-1(17), 2, 11, 13, 15-pentaene and meso-2, 12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17), 13,15-triene, respectively. All the compounds have the normal magnetic moments expected for Cu(II) complexes with S = ½. Conductance studies in methanol show that the halo-perchlorate complexes are formally five coordinate. The probable structures of the complexes in both the solid and solution are discussed in terms of their visible, infrared and e.s.r. spectra, as well as on the basis of data obtained from conventional polarography and cyclic voltammetry.
24 citations
22 citations
TL;DR: In this article, a graphical method for the determination of electrode reaction parameters (E1/2/r and αn) of the quasi-reversible processes has been proposed based on the use of the whole d.c. polarographic curve.
22 citations
TL;DR: A rapid polarographic method for the determination of chloramphenicol in milk is proposed and it is concluded that the drug undergoes a slow 2-electron reduction of the nitro group which is followed by a fast 2-Electron reduction to hydroxylamine.
TL;DR: In this paper, the formation of cadmium-ethylencdiaminetetraacetic acid (Cd-EDTA) in seawater and in sodium chloride solution has been studied by square-wave polarography.
Abstract: Complex formation of cadmium-ethylencdiaminetetraacetic acid (Cd-EDTA) in seawater and in sodium chloride solution has been studied by square-wave polarography. The rate of Cd-EDTA complex folmation in scawatcr is lower than that of the same reaction in the corresponding solution of sodium chloride or calcium and sodium chloride. The influence of chloride and calcium ions on complex formation of Cd-EDTA in sodium chloride solutions has been investigated and the results indicate that the degree of complex formation of cadmium with EDTA is diminished by the formation of cadmium monochloro complex and by the competition between calcium and cadmium.
TL;DR: A comparison of changes of u.v. absorption spectra and polarographic reduction waves with pH indicates that the reduction of 5-diethyl-amino-5-methyl-2-thiobarbituric (I) acid resembles in principle that of 5,5′-dialkyl-2 -thi-barbiturates, but that an additional acid-base equilibrium involving the exocyclic amino group is part of the electrode process.
01 Jan 1971
TL;DR: In this paper, a new interpretation of the appearance of Polarographic protein waves is proposed, and it has been proved that globular proteins are flattened or unfolded on the mercury surface.
Abstract: The importance of phenomena accompanying adsorption of a protein at the surface of the mercury electrode has been demonstrated. It has been proved that globular proteins are flattened or unfolded on the mercury surface. A new interpretation of the appearance of Polarographic protein waves is proposed.
TL;DR: In this paper, a theoretical analysis of the demodulation signal caused by the nonlinearity of the faradaic admittance is given for a plane, stationary electrode with a single step electrode process.
01 Jan 1971
TL;DR: In this article, the reduction behavior of N1-methyl nicotinamide iodide has been studied by drop-time controlled polarography in highly acidic media (below pH 3) two pH dependent waves were observed (I and I′) the latter having an abnormally high limiting current In the pH range of 3-10, two waves (II and III), the former being pHindependent whereas the E 1/2 of the latter shifted 60 mV per pH unit.
Abstract: The reduction behavior of N1-methyl nicotinamide iodide has been studied by drop-time controlled polarography In highly acidic media (below pH 3) two pH dependent waves were observed (I and I′) the latter having an abnormally high limiting current In the pH range of 3–10, two waves were observed (II and III), the former being pH-independent whereas the E 1/2 of the latter shifted — 60 mV per pH unit Evidence is presented for a chemical association step, possibly a dimerization occurring between reduction steps II and III Reoxidation of the reduction product of wave II was obtained at 740 mV above the potential of the wave II by cyclic voltammetry on stationary vitreous carbon electrodes This reoxidation peak is also pH independent
TL;DR: In this article, polarography of 8-hydroxyquinoline, 7-nitro-8-hydroxenequinoline-5-sulphonic acid and 8-hexene-quinoline 5-SCL was carried out in aqueous buffer with constant ionic strength (0·54 M) at 25 ± 0·1°C.
TL;DR: In this article, a rapid a.c. polarographic method was used for the analysis of the lead(II)/3-chloride/3-fluoride system.
TL;DR: The time-dependent decrease of the height of the wave characteristic for denatured DNA was ascribed to partial renaturation or/and aggregation of molecules, and the pre-melting observed polarographically mainly reflects changes of structure of DNA adsorbed on the surface of the mercury electrode.
TL;DR: In this paper, a polarographic method is described for qualitative and quantitative determination of 3-keto sugars, which is applied to establish the substrate specificity of the 3-ulose forming enzyme hexopyranoside: cytochrome c oxidoreductase.
TL;DR: The Pd2+-thiourea complex formed in perchloric acid medium in the presence of NaCIO4, has been extracted quantitatively into tri-N-butyl phosphate (TBP) supported as a stationary phase on a column of Voltalef.
Abstract: The Pd2+-thiourea complex formed in perchloric acid medium in the presence of NaCIO4., has been extracted quantitatively into tri-N-butyl phosphate (TBP) supported as a stationary phase on a column of Voltalef (polychloro-trifluoro ethylene). The complex was eluted with water and determined by atomic absorption spectrometry and polarography. Pd2+ can be estimated in the presence of Ir4+ and Au3+, but Pt4+ interferes seriously.
TL;DR: In this article, the fast ligand-replacement reaction of Ni(II) ion with pyridine in water has been investigated using the reaction-layer treatment of polarographic kinetic currents.
Abstract: The fast ligand-replacement reaction of Ni(II) ion with pyridine in water has been investigated using the reaction-layer treatment of polarographic kinetic currents. Comparison of present results with another polarographic investigation shows discrepancies which are explained. It appears that a surface reaction occurs at the dropping-mercury electrode; by taking this into account we have obtained a rate constant at 25° of 5 × 103 l. mol–1 s–1, and an activation energy of 14 kcal mol–1, in agreement with the values obtained by stopped-flow methods.
TL;DR: In this paper, an electrode reduction mechanism for two aromatic 2,5-substituted oxadiazoles in DMF solvent was reported, as part of a continuing study of the electrochemistry of five-membered nitrogen oxygen heterocyclics.
Abstract: An electrode reduction mechanism is reported for two aromatic‐2,5‐substituted oxadiazoles in DMF solvent as part of a continuing study of the electrochemistry of five‐membered nitrogen oxygen heterocyclics. Polarography, cyclic voltammetry, chronoamperometry, and uv spectroscopy were techniques employed in the study. The effects of a proton donor on the stability of reduction intermediates is discussed.
TL;DR: In this paper, the electroreduction of antimony (III) in sulphuric acid-thiocyanate solutions has been investigated by polarography and cyclic voltammetry.
TL;DR: In this article, a polarographic investigation of Pd(II) complexes has been conducted and the reduction wave potentials of these complexes were determined. But the results of the analysis were limited to the case of the chloro and bromo complexes, and no detectable change was observed in the case for the thiocyanato, nitro, and oxalato complexes.