Extraction of "Free Fatty Acids" from rodent blood

[John R. Carver]

I need to extract only "free fatty acids" from rodent blood without
rupturing the cell membrane follwed by G-C analysis. I have used
the following SPE procedure: First, remove all free Lipids with chloroform/
isopropanol then elute the free faty acids with acetic acid in diethyl ether.
Will this procedure remove only "FFA" and not rupture the cell membranes? All suggestions welcomed.

[Uwe Neue]

Your procedure looks rather incomplete.

If you do not want to "rupture the cell membranes" does this mean that you are only interested in the FA's in serum? I would then start with a centrifugation. Then we can think about a selective extraction, for example on an anion exchanger (Oasis MAX) with selected washing procedures. Also, your SPE method would make more sense if you would specify the type of SPE packing that you have explored.

[Fat Jonny]

See here:

http://www.sepsci.com/chromforum/viewtopic.php?t=9273

[HW Mueller]

John, is this your idea to separate "free" FA from other lipids via solvent extraction or did someone actually try this? I would be very surprised if one could get a clean enough separation even if one made the serum/pasma strongly basic before trying to extract lipids other than the "free" FA. (Actually, I am uncomfortable with this "free" terminology as FA stands for the acids, the bound ones are esters etc., while ~ all FA are adsorbed somewhere).
(incidentally, this is the post that didn´t go in yesterday)