Serum lipids may be separated by treatment with precipitant comprised of dilute polyethylene glycol at an alkaline pH. The larger, lipid-rich lipoproteins, VLDL and LDL form insoluble complexes more readily than do the smaller, protein-rich HDL. The insoluble complexes can be sedimented by low-speed centrifugation.
serum lipids + PEG precipitant -> HDL fraction + [LDL + VDL fractions]
The supernatant which contains the HDL fraction is then assayed for cholesterol using the Synermed Total Cholesterol reagent kit.