FATTY ACID COMPOSITION
OF PHOSPHOLIPIDS
The procedure used to analyze the fatty
acid composition of phospholipids is similar for an aliquot of purified phospholipids and
for isolated phospholipid classes but some differences in the derivatization time are
observed.
Reagents:
14% BF3 solution in methanol
Pentane, Hexane
Procedure:
Aliquots of a phospholipid solution are evaporated in a
screw-capped (Teflon-lined) tubes, 1 ml of BF3 solution is added and the
tightly closed tubes are treated during 90 min at 100°C (water bath or thermoblock).
After cooling to room temperature, the tubes are opened and after addition of 1 ml of
water and 2 ml of pentane they are vortexed for 1 min. After a short centrifugation, the
upper pentane layer is collected (without anay trace of the lower layer) and evaporated in
small glass tubes. The dry residue is dissolved in a small portion of hexane and the fatty
acid methyl esters are analyzed by GLC on a polar capillary column.
Scraped silica gel spots are treated with the same procedure but the methylation time is
adapted according to the chemical structure of the analyzed phospholipid.
Glycerophospholipids are derivatized for only 15 min while 90 min are required for
sphingomyelin (as for total phospholipid extracts which could contain this component).
