Two procedures to remove polar contaminants from a crude brain lipid extract by using prepacked reversed-phase columns.

Two procedures were developed using prepacked, reversed-phase columns (Bond Elut) for the separation of lipids from water-soluble contaminants. A crude lipid extract from brain tissue was diluted stepwise with a methanol/water (method or a methanol/saline (method mixture and, with each step, was passed through the column. As the polarity of the solvent was increased, all lipids became bound to the column, while the water-soluble compounds remained in the eluate. After three subsequent dilutions and column elutions, the eluate containing the more polar contaminants was discarded. The bound lipids were then eluted with a small volume of chloroform/methanol (1:2, v/v). Alternatively two fractions were eluted, the first fraction eluted with methanol/water (12:1, v/v), contained gangliosides, phosphatidylserine, phosphatidylinositol, phosphatidic acid and sulfatides. The second fraction, eluted with chloroform/methanol (1:2, v/v), contained all remaining phospholipids, cerebrosides and cholesterol. For both methods a quantitative recovery of cholesterol and phospholipids was obtained. In method 2, when water was replaced by saline in the dilution solvent mixture, gangliosides were also bound and quantitatively recovered.