Polarographic Investigation of Conjugated Fat-Soluble Vitamins

Kuta, E. J.

doi:10.1126/science.144.3622.1130

Cited by 13 publications

(2 citation statements)

References 7 publications

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“…However, when conducting the reductive electrolysis at 253 K, it was possible to record up to the transfer of 4e – per molecule, which indicates that the temperature has an effect on the electrochemical reduction of 1 . , There has been some controversy as to how many electrons are involved in the reduction reaction of 1 . Earlier studies by Takahashi and Tachi , and Kuta and Ju , suggested a 4e – reduction process, while Mairanovsky et al, Valentin Pfund et al, and Park suggested a 1e – process.…”

Section: Resultsmentioning

confidence: 92%

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Contrasting Voltammetric Behavior of Different Forms of Vitamin A in Aprotic Organic Solvents

2014

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Six of the major vitamers and provitamins comprising vitamin A (β-carotene, retinoic acid, retinol, retinyl palmitate, retinyl acetate, and retinal) were examined using voltammetric and controlled potential electrolysis techniques in the aprotic organic solvents acetonitrile and dichloromethane at glassy carbon and platinum electrodes. All of the compounds underwent oxidation and reduction processes and displayed a number of similarities and differences in terms of the number of redox processes and chemical reversibility of the voltammetric responses. The electrochemical properties of the compounds were strongly influenced by the functional groups on the unsaturated phytyl chains (carboxylic acid, alcohol, ester, or aldehyde groups), and not only on the fully conjugated hydrocarbon unit which is common to all forms of vitamin A. The compounds were reduced at potentials between approximately -1.7 and -2.6 vs (Fc/Fc(+))/V (Fc = ferrocene) and oxidized at potentials between approximately +0.2 and +0.7 vs (Fc/Fc(+))/V. The average number of electrons transferred per molecule under long time scale electrolysis experiments were found to vary between 0.4 and 4 electrons depending on the exact molecular structure and experimental conditions.

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Section: Resultsmentioning

confidence: 92%

“…33,37 There has been some controversy as to how many electrons are involved in the reduction reaction of 1. Earlier studies by Takahashi and Tachi 10,11 and Kuta and Ju 51,52 suggested a 4e − reduction process, while Mairanovsky et al, 23 Valentin Pfund et al, 24 and Park 14 suggested a 1e − process.…”

Section: Oxidative Cyclicmentioning

confidence: 95%

Contrasting Voltammetric Behavior of Different Forms of Vitamin A in Aprotic Organic Solvents

2014

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Electroanalysis and Biosensors in Clinical Chemistry

Killard

Sequeira

Diamond

et al. 2000

Encyclopedia of Analytical Chemistry

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Electroanalysis involves the measurement or determination of a chemical or biochemical species, using a wide range of electrochemical methods. The species being measured can either bring about a direct electrochemical response that can be detected and measured, or can be induced to bring about such a response, resulting in a process that can be detected electrochemically. In both cases an interface is required between the chemical or biochemical species being measured, and the electrochemical system performing the measurement. This interface is referred to as an “electrode”. It is the transfer of electrons or ions between the electrode and the environment being sampled which is of concern in electroanalysis. The application of electrochemistry in clinical analysis is concerned with the measurement of chemical and biochemical species present in biological fluids (primarily blood but also urine and other body fluids and tissues). It is applied in several areas of critical care where its rapidity, sensitivity, precision, and accuracy at biologically relevant concentrations make it an ideal choice over other, typically slower, biochemical techniques. Indeed, it is the speed of electrochemical analysis that principally differentiates it from other methods. It is not universally applicable to clinical chemistry, however, and has only been applied in situations where such analyses are relevant. This has principally been in the analysis of blood gases and pH and blood electrolytes. Electrochemical methods are, however, gradually being extended to the analysis of small biochemical components such as sugars, amino acids and other metabolites, with the advent of enzyme‐based “biosensors”. There is also little doubt that the application of electrochemistry in clinical analysis will be further exploited by the use of such biosensor devices based on other forms of biorecognition, such as antibodies, cell ligands, membranes, tissues and whole cells. These biosensor devices are also amenable to other forms of detection such as acoustic wave and optical measurements. Together, these techniques offer a wide range of advantages over traditional analytical methodologies, and will undoubtedly have a rapidly increasing impact on many types of clinical analysis. This article focuses on the use of electrochemical techniques and electrochemical biosensors and their application in clinical chemistry.

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Electron transfer from carbanionic salts to linear sequences of conjugated double bonds, 2. Reaction with trans‐β‐carotene

1989

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The reactions of a set of organoalkaline compounds with trans-p-carotene (Car) were studied in solution (using UV/Vis, ESR, and mass spectroscopy) and compared with the reactions of the same set with insoluble polyacetylene. It was shown that the naphthalene radical ion and the dicarbanionic dimer of 1, I-diphenylethylene, 1,1,4,4-tetraphenyl-l,4-butanediide, react with Car by a simple electron transfer leading to Car radical ion and dianion. This dianion is protonated by methanol mainly at carbon 7 or 7'. On the contrary of diphenylalkyllithium compounds add to Car double bonds. This addition of I mol of diphenylalkyllithium per Car takes place mainly at the central double bond. sec-Butyllithium (sec-BuLi) reacts also by addition to Car. The addition products are in some cases instable and decompose to radical ions through a non-elucidated mechanism. These transfer or addition reactions with Car, as well as the exclusive electron transfer observed with polyacetylene, are rationalized on the basis of the relative redox potentials of reactants. a) Part I : cf.".

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Polarographic Investigation of Conjugated Fat-Soluble Vitamins

Cited by 13 publications

References 7 publications

Contrasting Voltammetric Behavior of Different Forms of Vitamin A in Aprotic Organic Solvents

Contrasting Voltammetric Behavior of Different Forms of Vitamin A in Aprotic Organic Solvents

Electroanalysis and Biosensors in Clinical Chemistry

Electron transfer from carbanionic salts to linear sequences of conjugated double bonds, 2. Reaction with trans‐β‐carotene

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