Oxidation product identification

NO reactions, 383-384 oxidation products, identification, 376-377 SF reactions, 381 S02 reactions, 378,381 Polypropylene films, reflection infrared spectra, 179/... 

Forman, H. J. and Moore, K. E. 2013. Methods of lipid oxidation product identification and quantification. 59, 1-108. 

Product identification does not distinguish OH versus hole oxidation, because the products are identical. For example, the products identified in the photo oxidation of phenol (qv) (Fig. 7) may originate either by OH radical attack of the phenol ring, or by direct hole oxidation to give the cation radical which subsequendy undergoes hydration in solvent water. 

KHACHiK F BEECHER G R and GOLi M B (1992) Separation and identification of carotenoids and their oxidation products in the extracts of human plasma. Anal Chem. 64(18) 2111-22. 

The ready availability of carotenoid oxidation products through chemical methods will facilitate their use as standard identification tools in complex media such as biological fluids, and enable in vitro investigation of their biological activity. Moreover, these studies can help reveal the mechanisms by which they can be chemically or biochemically cleaved in vivo. 

Carotenoid oxidation products, as carotenoids, may exert protective or detrimental effects on human health. Efforts must be made to try to identify them in vivo where they may appear in lower quantities than carotenoids. Studies of abiotic systems can provide great support for their identification and the comprehension of their stability and reactivity. 

Stratton, S.P., Schaefer, W.H., and Liebler, D.C., Isolation and identification of singlet oxygen oxidation products of beta-carotene, Ghent. Res. Toxicol, 6, 542, 1993. 

McDowell DC, MM Huber, M Wagner, U von Gunten, TA Ternes (2005) Ozonation of carbamazepine in drinking water identification and kinetic study of major oxidation products. Environ Sci Technol 39 8014-8022. 

Lange CC, LP Wackett (1997) Oxidation of aliphatic olefins by toluene dioxygenase enzyme rates and product identification. J Bacterial 179 3858-3865. 

Figure 7.32 Identification of an oxidation product of Irganox 1330 by means of LC-APCI-MS...

Figure 7.32 shows the identification of an oxidation product of Irganox 1330 by means of APCI-MS. LC-APCI-MS/MS (high-resolution sector field-ion trap hybrid) has also been used for the analysis (elemental composition and structure) of Irganox PS 802 [636]. 

Hydrocarbons oxidize to give a complex mixture of products which include hydroperoxides, alcohols, ketones, acids, esters, etc. (1). Polyolefins similarly can be oxidized by heat, radiation or mechano-initiated processes. The precise identification and quantification of these oxidation products are essential for the complete understanding and control of these destructive reactions. Conventional methods for the identification of oxidation products include iodome-... 

NO Reactions. The most informative derivitization reaction of oxidized polyolefins that we have found for product identification is that with NO. The details of NO reactions with alcohols and hydroperoxides to give nitrites and nitrates respectively have been reported previously, and only the salient features are discussed here (23). The IR absorption bands of primary, secondary and tertiary nitrites and nitrates are shown in Table I. After NO treatment, y-oxidized LLDPE shows a sharp sym.-nitrate stretch at 1276 cm-1 and an antisym. stretch at 1631 cm-1 (Fig. 1), consistent with the IR spectra of model secondary nitrates. Only a small secondary or primary nitrite peak was formed at 778 cm-1. NO treatment of y-oxidized LLDPE which had been treated by iodometry (all -OOH converted to -OH) showed strong secondary nitrite absorptions, but only traces of primary nitrite, from primary alcohol groups (distinctive 1657 cm-1 absorption). However, primary products were more prominent in LLDPE after photo-oxidation. 

CH Nj reactions, 382 COClj reactions, 383 free radical addition of hexafluoroacetone, 257 identification of oxidation products CHjNj to measure peracids as peresters, 385 extinction coefficients, 388-389/ iodometry to measure -OOH, 385 NO to measure alcohols and hydroperoxides, 386 residual, simplified carbonyl envelope which results from SF exposure, 386... 

Khachik, F., Bernstein, P., and Garland, D. 1997. Identification of lutein and zeaxanthin oxidation products in human and monkey retinas. Invest. Ophtalmol. 38 1802-1811. 

Baker, D. L. et al. (1999). Reactions of beta-carotene with cigarette smoke oxidants. Identification of carotenoid oxidation products and evaluation of the prooxidant antioxidant effect. Chem. Res. Toxicol. 12(6) 535-543. Bonnie, T. Y. P. and Y. M. Choo (1999). Oxidation and thermal degradation of carotenoids. J. Oil Palm Res. 11(1) 62-78. 

Bodin, A., et al., Identification and allergenic activity of hydroxyaldehydes — anew type of oxidation product from an ethoxylated non-ionic surfactant, Contact Dermatitis, 44, 207, 2001. 

In summary, chemiluminescence is a sensitive, non-invasive technique that can measure reactive oxidant production by small numbers of neutrophils indeed, neutrophil-derived chemiluminescence can be detected in as little as 5 fA of unfractionated human blood. The assay is suitable for automation using either multichannel luminometers or luminescence microtitre plate readers. Many researchers, however, have questioned the usefulness of this technique because of the uncertainty of the nature of the oxidant(s) that are detected. Nevertheless, in view of the recent developments made towards the identification of the oxidants measured and the assay s ability to detect intracellular oxidant production, it is has an important place in the phagocyte research laboratory. 

Results of the present studies can be categorized as follow (i) identification of the electro-oxidation product of I- as L, (ii) reaction of iodine free radical with various substrates, (hi) reaction of iodine free radical with raw human blood samples. 

The peroxidase-catalyzed oxidation of ABTS (103) by H2O2 can also be performed by hydroperoxides, yielding a green-colored free radical. This reaction, catalyzed by HRP-C, was applied to the identification of an oxidation product of skatole isolated by HPLC, as a hydroperoxide (40). This assignment was confirmed by MS analysis (Section V.C.3) . 

Cytosine (Cyt) and 2 -deoxycytine (dCyd) hydroxyhydroperoxides generated by either OH radical or one-electron oxidation have been shown to be highly unstable, so far preventing their isolation and characterization by spectroscopic measurements such as NMR and MS. However, information is available on the chemical transformation of the 5- and 6-hydroperoxides as inferred from the isolation and identification of the main radical oxidation products of Cyt and dCyd. 

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