Plasma lipoproteins, preparative procedures

G4. Gidez, L. I, Miller, G. J., Burstein, M., and Eder, H. A., Analyses of plasma high density lipoprotein subclasses by a precipitation procedure Correlation with preparative and analytical ultracentrifugation. In Report of the High Density Lipoprotein Methodology Workshop (K. Lippel, ed.), pp. 328-340. U.S. Department of Health, Education and Welfare. NIH publication No. 79-1661, Bethesda, Md., 1979. 

In Table 1, sample preparation and cleanup procedures for vitamin K analysis using HPLC detection are shown, collected in groups of various sample matrices. A remarkable uniformity exists in the preparation of plasma samples. Almost every research group used identical solvents (ethanol in a volume ratio of 1 4) for denaturation of VK transport proteins (lipoproteins of the VLDL fraction) as well as for extraction of the vitamins from plasma (hexane in a volume ratio up to 20, depending on sample volume). MacCrehan et al. (77) and Sakon et al. (90) used isopropanol for denaturation, which is said to provide better extraction recoveries, but coextracted polar compounds may interfere with the vitamins in the final chromatography. The uniformity of this isolation process may be a result of former experiments, using strong acids, alkalines, or different extraction solvents and methods, which are summarized and discussed by Lambert et al. (17) in the second edition of this volume. 

---