Reduction Of Ceric Ion Research Articles

The chemical determination of liothyronine and thyroxine in enzymic hydrolysates of pork thyroid.

Abstract Maximum amounts of liothyronine and thyroxine were released from pork thyroid by the proteolytic action of erepsin and trypsin after incubation for 96 hr. at 39°. The iodinated thyronines were extracted from the hydrolysate with butanol, separated chromatographically, eluted from the paper and measured quantitatively by a chemical method in which the reduction of ceric ion by arsenious acid is catalysed by the iodine containing compounds. The iodine found in liothyronine and thyroxine accounted for 18 to 25 per cent of the total organic iodine in pork thyroid. It is postulated that pork thyroglobulin contains approximately 1 molar residue of liothyronine and 2 molar residues of thyroxine.

Radiolytic reduction of ceric ions in water DMSO mixtures and radioprotection

It is convenient to classify mechanisms of radioproteetion into those that involve fast radiation chemical processes and those in which the protection is the result of changes in the cell biochemistry. In the former, the added protectors have two principal effects: OH scavenging which reduces the radiosensitised damage and fast chemical repair processes involving hydrogen donation from the protector to the target radical. Typical of the first type of protector is dimethyl sulphoxide(DMSO)1 because it is known to be a good OH scavenger (kOH+DMSO =5×109 mol−1 s−1. (ref. 2). We have attempted to establish the redox properties of the OH radical adduct3 as well as those of H2O2 or H and HO2 radicals in water–DMSO mixtures. To this end we added to the solutions containing 0.5 M H2SO4, cerie ions at concentrations varying from 2.5 × 10−3 to 5 × 10−2 M. The Ce4+ reduction yield was determined as a function of the DMSO content in the solution, by irradiating the mixture with γ rays, in the presence or absence of air. The details of the experimental procedure will be given elsewhere. We report here that the yields (G) are independent of the Ce4+ concentration in the range studied and of the presence or absence of air, and depend only on the DMSO concentration.

Relationship between reduction of ceric ion with poly(vinyl alcohol) and graft copolymerization

AbstractVarious poly(vinyl alcohol) samples were preliminarily subjected to oxidation treatment with sodium hypochlorite, and the reduction of ceric ion and subsequently initiation in the graft copolymerization in the system containing methyl methacrylate were investigated. The reduction behavior of ceric ion could be subdivided into three parts, each of different reaction rate. In the initial stage of the reaction, there was observed rapid cleavage of the backbone chain of poly(vinyl alcohol) with ceric salts. The amount A of cleavage was proportional to the amount of ceric ion reduced at the initial fastest rate for various samples of different extents of oxidation; cleavage of 1 mole required ca. 10 moles of reduction of ceric ion. Higher carbonyl contents of the sample caused increased A. Graft polymerization was carried out in the same system with the addition of the monomer. The amounts of grafted chains produced were determined, and approximately one mole of grafted chains was obtained for per mole of cleavage. The copolymer is concluded to be blocklike in structure. The contribution of the carbonyl groups in poly(vinyl alcohol) sample to the initiation of the polymerization should be emphasized.

The Reduction of Ceric Ions by Po210 α-Particles

The Reduction of Ceric Ions by Po²¹⁰ α-Particles

THE DETERMINATION OF PROTEIN-BOUND IODINE

A method for the determination of protein-bound iodine in plasma is described. It is based essentially on the method of Barker, Humphrey, and Soley, which makes use of the catalytic effect of iodide on the reduction of ceric ion by arsenious acid. A number of improvements have been made in the direction of ease of manipulation and an over-all saving of time.

THE DETERMINATION OF PROTEIN-BOUND IODINE

A method for the determination of protein-bound iodine in plasma is described. It is based essentially on the method of Barker, Humphrey, and Soley, which makes use of the catalytic effect of iodide on the reduction of ceric ion by arsenious acid. A number of improvements have been made in the direction of ease of manipulation and an over-all saving of time.

THE REDUCTION OF CERIC SULPHATE SOLUTIONS BY IONIZING RADIATION

The yield of cerous ions formed in the reduction of ceric ion in sulphuric acid solutions by X and γ-radiation is independent of cerous and ceric ion concentration, the energy of the radiation, the rate of energy absorption over a wide range, the acid concentration, and the presence of oxygen. A small negative temperature coefficient has been observed. The over-all stoichiometric equation is[Formula: see text]Hydroxyl radicals postulated to be produced by the radiation form water and oxygen gas. The lower limit of concentration independence is below 2 × 10−6 moles per liter.

RADIATION CHEMISTRY INVESTIGATION OF AQUEOUS SOLUTIONS USING P32 AND S35 AS INTERNAL SOURCES

The oxidation of ferrous ion and the reduction of ceric ion in 0.80 N sulphuric acid by electrons from dissolved P32 and S35 have been studied. The chemical yields (chemical change per unit energy absorbed) obtained agree well with those obtained using X or γ-radiation. The yield is independent of electron energy above about 5 kev. The results show that chemical dosimetry methods may be used for the accurate determination of energy absorption for electron energies as low as 45 kev. or X rays of 200 kev.