Electron spin resonance spectrometry

Hydroxyl radical Spectrophotometry (532 nm) Electron spin resonance spectrometry... 

DPPH radical Electron spin resonance spectrometry Spectrophotometry (515-528 nm) Spectrophotometry/HPLC... 

Felby, C., Nielsen, B.R., Olesen, P.O. and Skibsted, L.H. (1997b). Identification and quantification of radical reaction intermediates by electron spin resonance spectrometry of laccase-catalyzed oxidation of wood fibres from beech (Fagus sylvatica). Applied Microbiology and Biotechnology, 48(4), 459 64. 

A number of studies have examined the antioxidant activities of chitosan from various sources. Park et al. (2004a) prepared three kinds of partially deacetylated hetero-chitosans such as 90% deacetylated, 75% deacetylated, and 50% deacetylated chitosan from crab chitin, and their antioxidant properties were measured using electron spin resonance spectrometry. Park and coworkers found that their antioxidant activities were dependent on the DD, and the 90% deacetylated chitosan showed the highest free radical scavenging activities. Yen et al. (2008) also found that a sample with more amino groups at the C-2 position showed the highest antioxidant activity. Tomida et al. (2009) examined the protective effects of seven different MW chitosans on plasma protein from oxidation by peroxyl radicals. In the ability to protect plasma protein from... 

The idea that free radicals occur in many chemical reactions is as old as the study of the mechanisms of these reactions. However, direct physical evidence for the existence of free radicals and for their presence in certain reactions is comparatively recent. Such evidence has been obtained in recent years by the methods of mass spectrometry, optical spectroscopy, and electron spin resonance spectrometry. The optical method of detecting free radicals has the advantage that it simultaneously supplies information about the structure of the radical. Indeed, in many instances the nature of the free radical has been identified by the structure of the spectrum without any assumptions about the mechanism of the reaction in which it appears.1... 

Riffaldi, and Schnitzer, M. (1972). Electron spin resonance spectrometry of humic substances. 

Many alternative techniques, both qualitative and quantitative, have been investigated either for screening purposes or as primary methods. Such techniques include atomic absorption spectrophotometry, molecular luminescence, electron spin resonance spectrometry, X-ray analysis methods, and electro analytical methods. Flameless atomic absorption spectrophotometry (FAAS) is the technique that has almost completely replaced NAA. 

Almeida et al. studied the oxidation of dipyridamole in acetonitrile and ethanol by voltammetric and spectroscopic methods [58]. The electrochemical oxidation of dipyridamole in acetonitrile and ethanol at high and low scan speeds was similar, and exhibited two reversible voltammetric waves corresponding to consecutive one-electron reactions. The Ei/2 values were 120 and 400 mV in acetonitrile, and 470 and 680 mV in ethanol. The release of one electron produced a radical cation which was detected by electron spin resonance spectrometry. The electrochemical oxidation of dipyridamole was accompanied by a decrease in fluorescence intensity at 470 nm, and significant changes in the ultraviolet-visible absorption... 

Kristensen, D., Skibsted, L.H. 1999. Comparison of three methods based on electron spin resonance spectrometry for evaluation of oxidative stability of processed cheese. J. Agric. Food Chem. 47, 3099-3104. 

Stapelfeldt, H., Nielsen, B.R., Skibsted, L.H. 1997b. Towards use of electron spin resonance spectrometry in quality control of milk powder. Correlation between sensory score of instant whole milk powders and concentration of free radicals and 2-thiobarbituric acid reactive substances. Milchwissenschaft. 52, 682-685. 

Heo, S. J., Park, P. J., Park, E. J., Kim, S. K., and Jeon, Y. J. 2005b. Antioxidant activity of enzymatic extracts from a brown seaweed Ecklonia cava by electron spin resonance spectrometry and comet assay. Ear. Food Res. Technol., 221,41-41. 

Burns DT, Eltayeb MAZ, Flockhart BD. 1987. Identification and determination of aromatic nitro-compounds by electron spin resonance spectrometry. Anal Chim Acta 200 481-490. 

The AAS method has several limitations. For the trace elements, particularly the colorants cobalt and nickel, the dilution factor required for analyses of 12 elements by continuous nebulization places these elements close to the detection limits for flame AAS. More accurate data on these and other trace elements are necessary before conclusions can be drawn on the source minerals used to impart color. Phosphorus, a ubiquitous minor component of medieval stained glass, has not been determined by AAS in the course of this work, but has the potential to provide key information on sources of plant ash. A full understanding of the colorant role of the transition metal elements is not possible on the basis of analysis alone UV-visible spectroscopy, electron spin resonance spectrometry, and Mossbauer spectroscopy, for example, are necessary adjuncts to achieve this aim. The results of the application of these techniques and the extension of the AAS method to trace element determination by pulse nebulization and furnace atomization will be addressed in future reports. 

Gamble, D. S., Schnitzer, M., and Skinner, D. S. (1977). Mn(II)-fulvic acid complexing equilibrium measurements by electron spin resonance spectrometry. Can. J. Soil Sci. 57, 47-53. 

Riffaldi, R. and Schnitzer, M. (1972a). Electron spin resonance spectrometry of humic sub-—Sihnces. Soil Sci. Soc. Am. Proc. 36, 301-305. 

Parman, T., Chen, G., and Wells, P.G., 1998, Prostaglandin H-synthase catalyzed bioactivation, electron spin resonance spectrometry and photochemical product analysis, J. Biol. Chem. 273, 25079-25088. 

Park, P.J., Je, J.Y., and Kim, S.K. 2003. Free radical scavenging activity of chitooligosaccharides by electron spin resonance spectrometry. J. Agric. Food Chem. 51 4624-4627. 

Electron spin resonance spectrometry has proven most helpful in studying mechanisms of reactions which proceed through free radical intermediates. 

Electron spin resonance spectrometry is one of the main methods to study transition metal containing metalloproteins, i.e., copper (cytochrome oxidase, superoxide dismutase), molybdenum (xanthine oxidase), and iron (cytochromes, ferredoxln, haemoglobin, etc.)... 

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