Testing methods electron spin resonance

Total antioxidant activities in 13 typical Italian wines were determined with an average of 12.3 pM Trolox equivalents for red wines and 1.6 pM for white wines (Simonetti et al., 1997). The values correlated well with total phenols (r = 0.9902) and flavanols (r = 0.9270) and clearly demonstrated that red wine polyphenols are significant in vitro antioxidants. The antioxidant capacity of 16 red wines from several countries was tested using electron spin resonance (ESR) spectroscopy (Bums et al., 2000). The antioxidant activity ranged from 4.13 x 1021 to 9.29 x 1021 number of Fremy s radicals reduced by 1 L of wine. The antioxidant capacity was associated with the phenolic content of the wines, determined either by Folin-Ciocalteau or by summation of the individual phenolics determined by HPLC or by spectroscopy. Total phenolics as measured by the Folin-Ciocalteau method ranged from 6.47 to 18.6 mM GAE per liter. The anthocyanin levels ranged from 101.5 to 325.7 pM. There were substantial differences in the proportion of polymeric pigments in the wines. 

The reliability and sensitivity of the probe method has been emphasised. It circumvents almost completely the perturbations inherent to some other probe techniques (electron spin resonance, fluorescence). In particular, free chains appear to be ideal, non-perturbative NMR probes for testing chain segment orientation in strained rubbers. The solvent probe method is easy to handle and unexpensive, since it does not require the synthesis of... 

Electron paramagnetic resonance (EPR), also called electron spin resonance (ESR) spectroscopy, is used to determine the electron spin for atoms with unpaired electrons. Most atoms have electrons that are paired together, because this makes them more stable. But radicals do not have spin pairs, and they can be tested using this method. Free radicals are often short-lived species, but they are also very important in the outcome of a chemical reaction. So when you can track their progress, you can better understand the mechanisms of chemical reactions. 

Lipid oxidation is also estimated by instrumental analyses such as by Rancimat test method and used for accelerated stability study [6]. Electron spin resonance can measure radical formation in many types of food matrices [7]. Analysis of volatiles with dynamic headspace/GC-MS is highly sensitive and can provide lot of information with regard to volatile lipid oxidation products and other volatiles with sensory impact in food samples. This type of data can also give information on possible reaction pathways of food deterioration [8]. Front-face fluorescence spectroscopy... 

Chromatographic techniques are the main methods that have been used to separate, detect, and identify organic components of FDR.152 162 Other methods considered include molecular luminescence,163 infrared spectroscopy,164 Raman spectroscopy,165 electron spin response spectrometry,166 microchemical crystal tests,167 168 ultraviolet spectroscopy/nuclear magnetic resonance/polarography.169... 

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