Plasma peroxide value

Peroxide Value, Fats and Oils (PV) (Cd 8-53) determines all substances, in terms of milliequivalents of peroxide per 1000 g of sample, that oxidize potassium iodide (KI). These substances generally are assumed to be peroxides or products of fat oxidation. Phosphorus in Oils (Ca 13-55) estimates the phospholipid content of crude, degummed, and refined vegetable oils in terms of phosphorus. Refineries often use induction coupled plasma (ICP) spectrographs to analyze divalent cations rapidly in aspirated crude oil. The calcium and magnesium measured are mainly responsible for nonhydratable phosphatides (NHP) and are determined directly. An AOCS method for analysis by ICP is being developed. 

A correlation may be established between the concentration of oxidized lipids and the TEARS value, expressed as MDA equivalents, in uM units. Correction is due in some cases for the interference by dyes or other factors. For example, the presence of anthocyanins in red cabbage leaves or turbiditjf causes overestimation of lipid hydroperoxides in plant tissue by the TEARS method. TEARS was used to assert the level of endogenous peroxides in hypo- and hyperthyroidism, both conditions being characterized by low lipid and lipoprotein plasma levels and enhanced oxidative metabolism . In a procedure for determination of TEARS in edible oils, the sample is placed in a centrifuge at 12000 g before measuring at 532 nm (e = 1.56 x 10 M cm ) . A usual procedure for determination of TEARS in certain complex matrices involves steam distillation of the aldehydes responsible for the value, instead of extraction. In nitrite-cured meats, excess nitrite may cause nitrosation of MDA, thus interfering with distillation. To avoid this interference sulfanilamide is added, which is converted to a diazonium salt and... 

This study on the immobilization of glucose oxidase and the characterization of its activity has demonstrated that a bioactive interface material may be prepared from derivatized plasma polymerized films. UV/Visible spectrophotometric analysis indicated that washed GOx-PPNVP/PEUU (2.4 cm2) had activity approximately equivalent to that of 13.4 nM GOx in 50 mM sodium acetate with a specific activity of 32.0 U/mg at pH 5.1 and room temperature. A sandwich-type thin-layer electrochemical cell was also used to qualitatively demonstrate the activity of 13.4 nM glucose oxidase under the same conditions. A quantitatively low specific activity value of 4.34 U/mg was obtained for the same enzyme solution by monitoring the hydrogen peroxide oxidation current using cyclic voltammetry. Incorporation of GOx-PPNVP/PEUU into the thin-layer allowed for the detection of immobilized enzyme activity in 0.2 M sodium phosphate (pH 5.2) at room temperature. 

Red cell GSPHx-1 and plasma GSPHx-3 are assayed by enzymatic methods using a variety of peroxide substrates, with tertiary-butyl peroxide being a commonly used substrate since it is not as affected by catalase as is hydrogen peroxide. The values obtained are dependent on the substrate used and the reaction conditions. During selenium supple-... 

Measurement of modified proteins may be an alternative or supplement to measuring products of peroxidation. Direct measurement of OxLDL in plasma appears to be a promising avenue for risk assessment in clinical laboratories. This technique utilizes ELISA that lends itself to automation. Studies indicate that elevated levels of OxLDL correlate with CAD and add predictive value to assessment by conventional lipoprotein lipids (El, H7, HIO, S12). Still, basic and clinical research is needed to determine exactly what is being measured, where it originates, and whether or not it is a cause of arteriosclerosis or only secondarily associated with it. Applied research is needed to determine how best to measure and standardize the assays, and randomized clinical studies are needed to determine the exact diagnostic usefulness. 

N2 + H2 the yields of products were found to depend on reaction time of the dissociated gases in the spatial afterglow rather than in the plasma itself. When the surface-to-volume (S/V) ratio of the spatial afterglow region was increased in experiments using dissociated water vapor the yield of hydrogen peroxide in a cold trap at 77 K increased to a maximum value and then decreased (Fig. 35). Only in one... 

Example 4-Hydroxynon-2-enal (4-HNE) is a major aldehydic product of lipid peroxidation (LPO), its products being indicators for oxidative stress. In order to introduce LPO products as biomarkers, a GC-MS method for 4-HNE detection in clinical studies [35] was developed using a sample volume of 50 pi of plasma. For improved GC separation and subsequent mass spectral detection the aldehyde is converted into the pentafluorobenzyl-hydroxylimine and the hydroxy group is tri-methylsilylated [36]. The TIC acquired in electron capture mode (EC, Chap. 7.4) exhibits 50 chromatographic peaks (Fig. 14.2). Those related to the target compounds can easily be identified from suitable RICs. The choice of potentially useful m/z values for RICs is made from the EC mass spectrum of the pure 4-HNE derivative (below). In this case, [M-HF], m/z 403, [M-HOSiMes] , m/z 333, and [CeFs]", m/z 167, are indicative, while [CH2C6F5] , m/z 181, is not. 

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