Polarography

About: Polarography is a(n) research topic. Over the lifetime, 4772 publication(s) have been published within this topic receiving 75478 citation(s).

Theory of Stationary Electrode Polarography. Single Scan and Cyclic Methods Applied to Reversible, Irreversible, and Kinetic Systems.

Abstract: was developed for solving the integral equations obtained from the boundary value problems, and extensive data were calculated which permit construction of stationary electrode polarograms from theory. Correlations of kinetic and experimental parameters made it possible to develop diagnostic criteria so that unknown systems can be characterized by studying the variation of peak current, half-peak potential, or ratio of anodic to cathodic peak currents as a function of rate of voltage scan.

[7] Mitochondrial respiratory control and the polarographic measurement of ADP : O ratios

Abstract: Publisher Summary This chapter discusses the mitochondrial respiratory control and the polarographic measurement of ADP : O ratios. The polarographic oxygen electrode technique is used for measuring rapid changes in the rate of oxygen utilization by cellular and subcellular systems. Although the polarographic method measures changes in oxygen concentration of photosynthetic systems, yeast cells, and nerve, but the oxygen electrode technique is applied to a study the mitochondrial respiration and oxidative phosphorytation. The principle of the oxygen electrode has been summarized, and the design of the vibrating oxygen electrode for use with speetrophotometric studies is illustrated. The oxygen electrode apparatus can be calibrated in a number of ways. A more accurate calibration of oxygen content can be obtained by gas equilibration with various nitrogen-oxygen mixtures. When tightly coupled mitochondria are suspended in an isotonic buffer, a slow rate of oxygen uptake is measured in the presence of substrate and absence of ADP. Addition of ADP causes an immediate increase in the rate of oxygen utilization. The concentration of oxygen utilized is proportional to the amount of ADP phosphorylated to ATP. The type of oxygen electrode tracings is presented from which an ADP : O ratio (equivalent to a P : O ratio) can be directly calculated.

Adsorption, autoinhibition and autocatalysis in polarography and in linear potential sweep voltammetry

Abstract: Summary The effects of a strong adsorption of the depolarizer and/or of the product of the electrochemical reaction on the currents obtained in polarography and in linear potential sweep voltammetry (l.p.s.v.) are considered. (a) A study of the surface electrochemical reaction (reaction of molecules in the adsorbed state) is presented. Mathematical expressions are derived for the current when the reaction is reversible (Brdicka prewaves or postwaves) for polarography and l.p.s.v. The case where the product of the reaction undergoes an irreversible chemical reaction of the first or second order in l.p.s.v. has been treated. Experimental examples are given: the theory accounts for the characteristics of the Brdicka prewaves and postwaves and of the adsorption peaks obtained in l.p.s.v. (b) The electrochemical process is modified by a film of adsorbed molecules (autoinhibition or autocatalysis). Three types of autoinhibition are considered: (I) The inhibiting film is constituted of the molecules of the depolarizer itself. (II) The molecules of the film result from a chemical reaction which occurs parallel with the inhibited electrochemical reaction. (III) The film is made of the final product of the inhibited electrochemical reaction. Mathematical expressions for the i−t curves and for the polarograms have been derived and experimental examples are given. In case III, autoinhibition waves similar in shape to Brdicka prewaves are often observed (pseudo-prewaves); criteria permitting a distinction to be made between prewaves and pseudo-waves are discussed. The case of an autocatalysis by the product of the reaction has been treated; an experimental example is given. The equations of the i−t curves (polarography) and i−E curves (l.p.s.v.) have also been calculated when the electrochemical reaction is irreversible. These equations are obeyed for small coverages. When the film of the depolarizer is compact anomalies appear, which are due to interactions between the molecules.

Recommendations on reporting electrode potentials in nonaqueous solvents (Recommendations 1983)

Abstract: On montre que les couples redox ferrocene/ion ferricenium, [ferrocene: bis(η-cyclopentadienyl) fer(II)] et bis(biphenyl) chrome(I)/bis(biphenyl)-chrome(o) peuvent etre utilises comme systemes redox de reference. On indique les procedes pour la mesure et le report des potentiels d'electrode dans des solvants non aqueux, vis-a-vis de ces systemes redox de reference. Donnees numeriques obtenues dans 22 solvants organiques