Lipid hydroperoxides titration methods

Oxidative stress Lipid oxidation Oxygen absorption Manometric, polarographic Diene conjugation HPLC, spectrophotometry (234 nm) Lipid hydroperoxides HPLC, GC-MS, chemiluminescence, spectrophotometry Iodine liberation Titration Thiocyanate Spectrophotometry (500 nm) Hydrocarbons GC Cytotoxic aldehydes LPO-586, HPLC, GC, GC-MS Hexanal and related end products Sensory, physicochemical, Cu(II) induction method, GC TBARS Spectrophotometry (532-535 nm), HPLC Rancimat Conductivity F2-iP GC/MS, HPLC/MS, immunoassays... 

Hydroperoxides may be determined by measuring at 290 nm (e = 44100 M cm ) or 360 nm (e = 28000 cm ) the concentration of 13 formed in the presence of a large excess of ions. The reaction may be too slow for practical purposes, unless a catalyst is present. For example, an assay for lipid hydroperoxides conducted without a catalyst may require several measurements every 6 min until the absorbance reaches a maximum. Exclusion of air from the sample cuvette is important. The method is about 1000-fold more sensitive than thiosulfate titration The iodometric method with UVD at 360 was adopted for detecting the presence of hydroperoxides derived from protein, peptide or amino acid substrates subjected to y-radiation, after destroying the generated H2O2 with catalase. ... 

Iodine liberation is one of the oldest and most commonly used methods for assessing lipid substrate oxidation. In this method, hydroperoxides and peroxides oxidize aqueous iodide to iodine, which is then titrated with standard thiosulfate solution and starch as endpoint indicator. The peroxide value is calculated as milliequivalents of peroxide oxygen per kilogram of sample. 

Consequently, in addition to hydroperoxides, a lot of secondary oxidized lipidic compounds, mainly short-chain aldehydes, may appear and represent late markers of lipid peroxidation. As an example, malondialdehyde (MDA, Fig. 6) is known to be the most abundant lipid peroxidation aldehyde whose determination by 2-thiobarbituric acid (TBA) is one ofthe most common assays in lipid peroxidation studies [20]. However, it can be noticed that the TBA assay method [21] is not specific of MDA titration since it also can detect a variety of peroxides and secondary degradation products of lipid peroxidation called... 

This method is one of the oldest and most commonly used measurements of the extent of oxidation in oils. The standard iodometric procedures measure by titration, or colorimetric or electrometric methods, the iodine produced by potassium iodide added as a reducing agent to the oxidized sample dissolved in a chloroform-acetic acid mixture. The liberated iodine is titrated with standard sodium thiosulfate to a starch endpoint. The peroxide value (PV) is expressed as milliequivalents of iodine per kg of lipid (meq/kg), or as millimole of hydroperoxide per kg of lipid (referred to as peroxide). PV expressed as meq/ Kg = 2 X PV mmol/kg. 

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