Lipid extraction from blood and biological samples and concentrations of dioxin-like compounds.

The extraction of lipid from human blood and other biological materials in the determination of dioxin-like and organochlorine compounds has been studies using different amounts of extracting solvent. When large volumes of ethanol-hexane are used to extract small blood samples, the total lipid extracted is incomplete as the polar phospholipids do not partition into the organic phase. This failure to extract all the blood lipid results in an inaccurately high concentration expressed on a lipid basis and, by corollary, a high biased body burden. This solvent dependence of lipid extraction does not appear to be a problem for most other biological and food samples since over 90% of the lipid is in the form of readily extractable neutral glycerides.