Showing papers on "Polarography published in 1979"
••
TL;DR: The faradaic and non-faradaic processes taking place at the interface of two immiscible electrolyte solutions have been compared with analogous processes occurring at interface metal-electrolyte solution as discussed by the authors.
336 citations
••
327 citations
••
TL;DR: The expression of the faradaic impedance in the case of a quasi-reversible system O+ne R under the following conditions: (a) both oxidized and reduced forms are strongly adsorbed; (b) the adsorption rate is large, and does not control the kinetics of the system; and (c) the adaption of both O and R obeys a Langmuir isotherm.
138 citations
••
TL;DR: A detailed qualitative investigation of the behavior of lead complexes with fulvic substances has been carried out using several polarographic techniques, e.g. d.c. polarography, normal and differential pulse polarography and cyclic voltammetry.
88 citations
••
TL;DR: In this paper, a model for the electrode process corresponding to the reduction of Pb(II) complexed by fulvic substances is presented and a mathematical expression is given for the polarographic wave.
65 citations
••
TL;DR: An immunological method based on labeling an antigen with an electroactive group detectable by differential pulse polarography has been demonstrated and is potentially useful as an analytical immunological technique.
Abstract: An immunological method based on labeling an antigen with an electroactive group detectable by differential pulse polarography has been demonstrated. Estriol labeled with mercuric acetate is electroactive, giving a reduction wave at -300 millivolts versus a standard calomel electrode. Addition of estriol antibody to 4-mercuric acetate estriol diminishes the peak current as a result of the antigen-antibody binding reaction. Separation of free-labeled estriol from antibody-bound-labeled antigen is unnecessary. The method is potentially useful as an analytical immunological technique.
59 citations
••
TL;DR: In this article, different concentrations of non-specifically and specifically adsorbed supporting electrolytes were employed to change the potential φd at the outer Helmholtz plane and/or the charge density qi at the inner Helm-holtz planes.
39 citations
••
TL;DR: In this article, a polarographic detector is described and its performance is compared with that of a commercial solid-state amperometric detector using a glassy carbon electrode and with a UV detector.
38 citations
••
TL;DR: In this article, the potentials of the Eu(III)/Eu(II) couple, cobalticinium ion/cobaltocene, Cic+/Coc, system and bisdiphenylchromium (I/O)/ (BPC) in the whole composition range (except for pure acetone) have been measured.
36 citations
••
TL;DR: In this article, strongly chelating anthraquinones and their derivatives were studied by d.c. polarography, cyclic voltammetry and micro-coulometry to investigate their redox characteristics.
Abstract: Analytically important, strongly chelating anthraquinones and their derivatives were studied by d.c. polarography, cyclic voltammetry and micro-coulometry to investigate their redox characteristics. All 18 substances were reduced in a two-electron reversible or quasi-reversible process in both aqueous and 75% ethanolic solutions. Depending on pH and the medium, single or double polarographic reduction waves appeared, which were diffusion controlled, although in some instances adsorption pre-waves were also observed. This behaviour is similar to the known behaviour of simpler quinone systems. The variation of the Ilkovic coefficient and half-wave potential with pH was studied in detail to investigate the acid-base behaviour of the species involved in the reduction process. As a result, it was possible to describe the reduction mechanism of the anthraquinones involved.A number of new pK values were determined and others confirmed. Attempts to find linear free energy relationships were generally unsuccessful.
35 citations
••
TL;DR: A new flow-through cell is described for application of the dropping mercury electrode to the determination of serum proteins in an automated continuous-flow system and it is possible to run a rapid automated system at sampling rates of up to 120 per hour with approximately +/- 1% precision and less than 3% carry-over.
••
TL;DR: The electrochemistry of technetium was studied by polarography, cyclic voltammetry and coulometry in chloride and sulfate media as a function of pH in the range 1.5-13 as discussed by the authors.
••
TL;DR: Theoretical equations for the surface redox reaction (Oad+neightleftharpoonsRad) in which charge transfer reaction takes place exclusively between the adsorbed reactants Oad and Rad, and both reactants are adorbed so strongly that the amount of O or R brought to or removed from the electrode surface can be neglected are presented in this paper.
Abstract: Theoretical equations are presented of the a.c. polarization and of the a.c. polarography and voltammetry for the surface redox reaction (Oad+ne\ightleftharpoonsRad) in which charge transfer reaction takes place exclusively between the adsorbed reactants Oad and Rad, and both reactants are adsorbed so strongly that the amount of O or R brought to or removed from the electrode surface can be neglected. The interaction between adsorbed molecules is assumed to be expressed by Frumkin’s a-parameters. Also the effect of the double layer impedance is taken into account. Some simplified cases are discussed in detail.
••
TL;DR: Differential pulse polarography has been shown to be capable of measuring sulphide directly in untreated natural water samples as mentioned in this paper, which is the preferred technique for direct colorimetry and is in good agreement with direct colourimetry, and can be used to assess the applicability of a particular calibration technique.
••
TL;DR: In this article, the polarographic behavior of the dropped mercury drop electrode and the stationary platinum electrode in acetonitrile has been studied in the presence of a dropping mercury electrode and large scale electrolysis was employed to obtain information on reaction products.
••
TL;DR: In this article, an explicit equation which is valid without any limitation in the magnitude of rate constant of the chemical reaction involved, is derived in a rigorous way, for the d.c. polarographic instantaneous (and average) current-potential curves with a c.e. mechanism accompanied by nernstian behaviour.
••
TL;DR: In this paper, an equation for stripping polarography is derived,relating the half-wave potential (E* 1 2 ), ligand concentration, and dissociation constant of a complexed metal ion.
••
TL;DR: In this article, it was shown that Zr(IV) catalysis of the reduction of nitrate at mercury electrodes occur because of electrostatic interaction of the nitrate with adsorbed Zr (IV), and the overall process is an 8electron reduction to ammonia.
••
TL;DR: In this paper, the adsorption and association of cytidine sulphate have been studied by using phase-sensitive ac-polarography in acidic buffer solution (pH 3.24) at the dropping mercury electrode.
Abstract: The adsorption and association of cytidine sulphate have been studied by using phase-sensitive ac-polarography in acidic buffer solution (pH 3.24) at the dropping mercury electrode. At low bulk con...
••
TL;DR: In this paper, a mechanism was proposed which serves to explain the effects of some important variables on the electrochemical behavior of technetium, on the basis of diagnostic criteria, which served to explain how important variables can affect the performance of the reduction process.
••
TL;DR: Polarographic detection offers greater sensitivity for theophylline than UV detection; further,erences which hamper UV detection may be selectively eliminated with polarographic detection.
••
TL;DR: In this paper, the optimum conditions of electrolyte composition and pH were studied for the cathode ray polarography (c.r.p.) of the catalytic molybdenum(VI) wave.
••
TL;DR: In this paper, the relationship between peak potentials and pH was analyzed and the yields of the degradation products were significantly affected by the presence of molecular oxygen. But the relationship was not discussed.
••
TL;DR: In this article, the process of electroreduction of cobalt(II) in thiocyanate solutions at mercury electrodes has been investigated by cyclic voltammetric, chronoamperometric and polarographic methods.
••
TL;DR: In this paper, the ring carbonyl group of xylenol orange is reduced in two one-electron steps at a dropping mercury electrode, and the half-wave potentials of both steps depend on pH, for the products of reduction, the dye radical formed in step I and the OH group produced in step II behave as acids.
••
TL;DR: In this paper, the kinetic parameters of the Ni(II)/Ni(Hg) system in thiocynate solutions have been determined using pulse chronocoulometric polarography.
••
TL;DR: In this paper, a polarographic method has been developed for the assay of catecholamines in pharmaceutical preparations using differential pulse polarography peak current was found to be linearly related to catecholine concentration and the glassy carbon surface was not fouled by the products of the electrochemical oxidation.
••
TL;DR: In this article, the direct current and differential pulse polarographic behavior of the sulfhydryl group of penicillamine in 0.056 M citrate buffer of pH 6.45 was investigated.
••
TL;DR: In this paper, it was shown that the Brinkman and Los equation for the instantaneous limiting current of a catalytic process in pulse polarography, which allows variation of the values of the pulse time t without restrictions, does allow, without computation troubles, to vary the χ=(κ 1 +κ 2 ) t values without limitation, where κ 1 and κ 2 are the rate constants of the chemical reactions.
••
TL;DR: In this article, the electronics and construction of a low cost, low noise triangle wave generator suitable for cyclic voltammetry, polarography, anodic stripping voltameters, and other electrochemical applications are described.
Abstract: The electronics and construction of a low cost, low noise triangle wave generator suitable for cyclic voltammetry, polarography, anodic stripping voltammetry, and other electrochemical applications are described. Components for the unit cost about S200.