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Showing papers on "Polarography published in 1983"



Journal ArticleDOI
TL;DR: It has been shown that DNA modified with osmium (DNA-Os) accumulates at the hanging mercury-drop electrode during a waiting time in a wide range of potentials and will produce at neutral pH a well-developed reduction peak at about -1.2 V due to scanning in the cathodic direction.

80 citations


Journal ArticleDOI
TL;DR: The electronic and e.s.r. spectral data of the copper and cobalt chelates of tetra-2,3-pyridinoporphyrazine showed that the electronic environment provided by the ligand is similar to that of the phthalocyanines as discussed by the authors.
Abstract: The electronic and e.s.r. spectral data of the copper(II) and cobalt(II) chelates of tetra-2,3-pyridinoporphyrazine show that the electronic environment provided by the ligand is similar to that of the phthalocyanines. Potentiometric pH, spectrophotometric, and e.s.r. spectral measurements show that the water soluble NN′N″N‴-tetramethyl quaternized tetracationic forms of the copper(II) and cobalt(II) tetra-2,3-pyridinoporphyrazinates are free of solute-solute interactions, stable in a wide range of acidic solutions, but give rise to some decomposition in slightly alkaline solution. The cobalt(II) chelate forms five- and six-co-ordinate complexes with certain heterocyclic nitrogen ligands. The e.s.r. spectrum due to the imidazole complex of cobalt(II)NN′N″N‴-tetramethyltetra-2,3-pyridinoporphyrazinate indicates an unusual ground state of cobalt(II) in these circumstances. Spectrophotometric and e.s.r. spectral data indicate that the cobalt(II) chelate in aqueous solution undergoes a one-electron reduction of the metal centre as a result of reaction with ascorbic acid. The d.c. polarographic behaviour of the cobalt(II), nickel(II), and copper(II) chelates consists of waves with E½ in the region of –0.55 and –1.20 V versus the saturated calomel electrode. The waves are polarographically irreversible but it has been shown that the first wave is due to a one-electron reduction of the chelates at the dropping mercury electrode.

51 citations


Journal ArticleDOI
TL;DR: In this article, the determintation of cefadroxil, cephalexin and cephapirin is described and the calibration graph is linear over the range 10 -3 −5 × 1 -7 M. Mechanisms are discussed.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the large shifts in formal potentials (vs ferrocene/ferricinium internal standard) are interpreted on the basis of Gutmann's donor-acceptor concept for solvent-solute interaction.

49 citations


Journal ArticleDOI
TL;DR: In this article, the effect of sphericity on current-time relationships at potentiostatted electrodes has been examined for cases of polarographic reductions to amalgamable metals and it is demonstrated that the customary plots of ln( i d − i )/i versus potential are without quantitative significance.

41 citations


Journal ArticleDOI
TL;DR: By raising the detector cell temperature, the detector response to cis-dichlorodiammineplatinum(II) (DDP) can be shifted anodically to 0.0 V vs. Ag/AgCl, thereby increasing detector selectivity for this compound.

40 citations


Journal ArticleDOI
01 Dec 1983-Talanta
TL;DR: A procedure based on differential pulse polarography is described for the determination of manganese at ng ml levels in fresh, estuarine and sea-water buffered at pH 9.5 with a citrate-borate solution that also serves as supporting electrolyte.

36 citations


Journal ArticleDOI
TL;DR: In this article, the electrochemical reduction of cimetidine, an H 2 -antagonist of histamine used in the treatment of duodenal and gastric ulcers, has been examined by using a variety of electrochemical techniques.

34 citations


Journal ArticleDOI
01 Jan 1983-Analyst
TL;DR: Good agreement was obtained between results with the differential-pulse polarography method and those by the manufacturer's method of assay, which involves the transfer of four electrons as well as dehydration and deamination steps in acid solution.
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.

28 citations


Journal ArticleDOI
W. J. van Oort1, R.H.A. Sorel1, D Brussee1, S.G Schulman1, P Zuman1, J. Den Hartigh1 
TL;DR: In this article, a differential pulse polarographic method for the determination of 10 −5 −10 −6 M nalidixic acid and its metabolite, the 7-hydroxymethyl derivative, in urine was developed; only a simple extraction is needed.

Journal ArticleDOI
TL;DR: In this article, simple approximate equations for peak current ratio and peak potentials have been presented in terms of relevant parameters such as diffusion coefficient of metal in mercury, that of ion in solution, electrode radius, potential sweep rate and switching potential.

Journal ArticleDOI
TL;DR: In this paper, the binding of a reducible drug, diazepam, to human serum albumin has been studied by high-performance liquid chromatography and by differential pulse polarography with a static mercury drop, over a wide range of protein concentrations.

Journal ArticleDOI
TL;DR: In this article, the theoretical treatment of diffusion-limited, reversible electrode reactions with adsorption of reactant and/or product of the reaction under potentiostatic conditions, developed by Reinmuth and Balasubramanian in 1972, is extended, thus permitting the study of ad-otherms of the more usual kind (Langmuir, Frumkin, etc.) as well as other more complex types (e.g. multilayers, experimental isotherms…).


Journal ArticleDOI
TL;DR: In this article, the authors used dc polarography, differential pulse polarography (DPP), cyclic voltammetry, controlled potential electrolysis, and chronoamperometry to study the electrochemical reduction of methylcobalamin and coenzyme B12.

Journal ArticleDOI
TL;DR: A rotating disk electrode coated with a thin mercury film is described, suitable for electrochemical determinations of the catalytic constant of superoxide dismutase in a much wider pH range than that accessible to polarographic methods.



Journal ArticleDOI
TL;DR: In this paper, a linear relationship was found between the half-wave potential and the sum of the Hammett constants of the substituents of ligands, which indicated the importance of the local charge distribution on the complex anion.
Abstract: In tetraethylammonium perchlorate–acetonitrile solution, [Ru(R1–CO–CR2–CO–R3)3] (R1,R3=–CH3, –CF3, –C6H5, –C(CH3)3; R2=–H, –C6H5) was reversibly reduced at a dropping mercury electrode to the corresponding univalent anion. A linear relationship was found between the half-wave potential and the sum of the Hammett constants of the substituents of ligands. In some cases, the polarogram and the cyclic voltammogram were shifted to more positive potentials in the presence of lithium or sodium ions. This effect was explained quantitatively by the two-step association between the reduction product, [Ru(R1–CO–CR2–CO–R3)3]−, and alkali metal ions. The association constants were calculated. The K2 values were appreciable and the K1 values were much larger than expected for a simple electrostatic interaction. Furthermore, the K1 values were linearly related to the sum of the Hammett constants of the substituents of the ligands. These results suggest the importance of the local charge distribution on the complex anion...

Journal ArticleDOI
TL;DR: In this article, the electrochemical oscillations of the system Hg, HSO−4, BrO−3 and phenol are described, and the temporal change of the limiting current and that of surface-tension of mercury oscillate in an anodic, anodic-cathodic or cathodic range depending on the concentration of phenol and the value of the dme potential.

Journal ArticleDOI
01 Apr 1983-Talanta
TL;DR: A method has been developed for determination of platinum in urine, after administration of cis-dichlorodiammineplatinum(II), which yields a catalytic current at a dropping mercury electrode, measurable by differential pulse polarography.

Journal ArticleDOI
TL;DR: The polarographic behavior of dithiole-thiones in DMF depends on the nature of substituent R4 as discussed by the authors, and the 2 e cathodic wave occurs at ca. −1050 mV vs. aqueous SCE.

Journal ArticleDOI
TL;DR: In this paper, the reduction of heavy metals (cadmium, lead and zinc) in the presence of long-chain fatty acids (lauric, oleic and linoleic) in 0.55 and 0.03 mol dm−3 NaHCO3 at pH 8.7 has been studied by differential pulse polarography.

Journal ArticleDOI
TL;DR: High-performance liquid chromatographic separation of a number of biologically important pyrimidine derivatives was studied in the reversed-phase system and the use of two or three detectors in series improves the resolution of complex mixtures and facilitates identification.

Journal ArticleDOI
TL;DR: In this article, a polarographic high-performance liquid chromatographic detector has been constructed in which the effluent is directed horizontally onto a vertical macroscopic mercury drop electrode in a microscopic electrolysis cell.

Journal ArticleDOI
TL;DR: The use of differential pulse polarography for the analysis of 1,4-benzodiazepines in body fluids is well documented as mentioned in this paper, but the major drawback of the technique is the need for a thin layer chromatographic separation prior to polarographic measurement to ensure specificity in the measurement of a 1, 4 benzodiazepine in the presence of its metabolites.

Journal ArticleDOI
TL;DR: In this paper, a comparative study of 2-benzoylpyridine hydrazone and azine has been carried out by using classic and differential pulse polarography techniques, and mechanisms for the reduction of the compounds are proposed.

Journal ArticleDOI
TL;DR: In this paper, a reduction mechanism was proposed for trimethyllead in seawater using differential pulse polarography and reverse normal pulse voltammetry (RPNV) to distinguish between inorganic and organic forms of lead.

Journal ArticleDOI
TL;DR: In this paper, the Riemann-Liouville transform (RLT) polarogram was used for the numerical determination of kf and kc from digitally acquired i(t) data.