Protein Carbonyl Measurement by a Sensitive ELISA Method

Protein damage and degradation by oxygen radicals. III. Modification of secondary and tertiary structure.

The mechanism of synthesis of amino acids by electric discharges.

Alizarin red undergoes rapid photoassisted decomposition in air-equilibrated aqueous TiO2 dispersions under visible light radiation (λ > 420 nm). Proton NMR, chemical oxygen demand (CODCr), UV−visible, IR, GC−MS, and spin-trapping ESR spectroscopic techniques were employed to obtain details of the photodegradation of alizarin red. Peroxides and carbonyl species are the first intermediates observed during the process. The major component of the peroxides produced is H2O2, and no organoperoxides were detected. We have also confirmed that in addition to CO2 and to smaller carbonyl species the principal intermediate produced is phthalic acid, which is unable to degrade further because it does not absorb the actinic visible light radiation (λ > 420 nm). The photodegradation kinetics are discussed in terms of the Langmuir−Hinshelwood model, a case of saturation type kinetics. A mechanism for the photoassisted degradation of alizarin red mediated by TiO2 particles under visible light radiation is proposed.

Photoassisted Degradation of Dye Pollutants. 8. Irreversible Degradation of Alizarin Red under Visible Light Radiation in Air-Equilibrated Aqueous TiO2 Dispersions

A convenient method for the quantitative determination of the carbonyl compounds in fats and oils is described. The procedure is based upon the formation of the 2,4-dinitrophenyl hydrazones of the carbonyl compounds in the presence of trichloroacetic acid catalyst and the colorimetric determination of the hydrazone compounds in alkaline solution. Standardizations are presented for the simultaneous determination of saturated and allenic carbonyl content from the absorbences at 430 and 460 mµ. Applications of these procedures to edible oils are described, and data are presented showing the carbonyl values in relation to other criteria of change. The problem of correlating changes in the carbonyl content of oils with flavor deterioration is now under investigation.

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Leland Clark

Papers

Colorimetric Method for Determination of Traces of Carbonyl Compounds