Secondary lipid analysis

D2.2 Chromatographic Analysis of Secondary Lipid Oxidation Products... 

Thiobarbituric acid (TBA), secondary lipid oxidation products analysis, 535... 

Lipid oxidation was monitored through analysis of the hydroperoxide content measured via the ferric thiocyanate method [64]. Oil was extracted from an aqueous emulsion prepared from the microcapsules using isooctane/2-propanol 50 50 (v/v). Headspace gas chromatographic analysis of secondary lipid oxidation products was performed in the majority of trials, but since correlation of propanal as a key compound was always very good with the hydroperoxide content, data are not reported in this chapter. 

The detection and quantification of one or more of the above lipid peroxidation produas (primary and/or secondary) in appropriate biofluids and tissue samples serves to provide indices of lipid peroxidation both in ntro and in vivo. However, it must be stressed that it is absolutely essential to ensure that the products monitored do not arise artifactually, a very difiScult task since parameters such as the availability of catalytic trace metal ions and O2, temperature and exposure to light are all capable of promoting the oxidative deterioration of PUFAs. Indeed, one sensible precaution involves the treatment of samples for analysis with sufficient levels of a chainbreaking antioxidant [for example, butylated hydroxy-toluene (BHT)] immediately after collection to retard or prevent peroxidation occurring during periods of storage or preparation. 

K. Keune and J. J. Boon, Enhancement of the static SIMS secondary ion yields of lipid moieties by ultrathin gold coating of aged oil paint surfaces, Surface and Interface Analysis, 36, 1620 1628 (2004b). 

Although information on the spatial distribution of membrane lipids can be important (3), most mass-spectrometric approaches used in lipidomics focus currently on the determination of total lipid composition. An advanced mass-spectrometric surface analysis technique, however, secondary ion mass spectrometry (SIMS) determines lipid compositions within different areas of freeze-fractured cells (12). This technique and related imaging techniques will become important tools in lipidomics. 

Analysis Measure relatively low levels of oxidation (below 1%) and include measurement of initial or primary products of lipid oxidation (e.g., hydroperoxides, conjugated dienes) as well as secondary decomposition products of lipid oxidation (e.g., carbonyls, volatiles, dialdehydes). 

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