Abstract
By partitioning the lipids obtained from 0.1 ml of serum in a binary system formed of 87% ethanol and petroleum ether, the total amount of glycerides, free cholesterol, and cholesterol esters present in the serum is quantitatively determined. By three partitions carried out with 3 ml of the upper phase and 1 ml of the lower phase of the aforesaid binary system, a phospholipid-free petroleum ether solution containing the total amount of the glycerides present in the serum is obtained. The glyceride content of this solution is determined by glycerol analysis. Three partitions of serum lipids carried out with 1 ml of the upper phase and 5 ml of the lower phase of the same binary system lead to a complete removal of free cholesterol. The cholesterol ester content of the serum is thus measured by a cholesterol determination on the final petroleum ether upper phase. The free cholesterol content of the serum is measured by a cholesterol determination carried out on the combined lower phases isolated during the cholesterol ester determination.
Highlights
Three partitions of serum lipids carried out with 1 ml of the upper phase and 5 ml of the lower phase of the same binary system lead to a complete removal of free cholesterol.The cholesterol ester content of the serum is measured by a cholesterol determination on the final petroleum ether upper phase
As PREVIOUSLY reported
Glycerides are recovered from the upper phase, while phospholipids are distributed with a partition ratio of about 6
Summary
A sample of 0.1 ml of serum is pipetted into a tube containing 2 ml of absolute ethanol-petroleum ether 1:l (v/v) and the tube is placed for about 1 min in a boiling water bath. (Petroleum ether of bp 40-70' was used throughout this investigation.) After cooling at room temperature, 6 ml of petroleum ether are added and the contents of the tube are mixed by gentle swirling. A sample of 0.1 ml of serum is pipetted into a tube containing 2 ml of absolute ethanol-petroleum ether 1:l (v/v) and the tube is placed for about 1 min in a boiling water bath. (Petroleum ether of bp 40-70' was used throughout this investigation.) After cooling at room temperature, 6 ml of petroleum ether are added and the contents of the tube are mixed by gentle swirling. Water (1 ml) is added, the mixture is gently swirled and allowed to stand at room temperature for 2 to 3 min. The upper phase of the binary system formed is transferred quantitatively into a 10 ml volumetric flask, using small portions of petroleum ether, and adjusted to volume with the same solvent
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