Good morning,
I am interested in FA analysis {GC-FID} in human milk. Now I have a problem with extraction of total lipids from milk. Is there anybody who have an experince with solid phase extraction of fat? I use supelco LC-18 tubes (6 ml, 0.5g) but I have a problem with clogging by proteins. But if I remove the proteins (HCl and centrifugation) in the same time a lot of fat is removed. I used too classic method (Folche) but the result were similar.
If anybody can help me, please contact me by mail
pmarhol@lf3.cuni.cz

thanks all

Petr

Try the extraction described in
EG Bligh and WJ Dyer, Can J Biochem Physiol, 37 (or 35?), 911-917 (1959). These authors used an extraction of lipids which employed ONE LIQUID phase in the first extraction step, rather than two liquid phases employed by Folch. Also, you may need to adjust your pH to be more acidic prior to the extraction.

why not precipitate the proteins with an organic solvent? this should keep your lipid desolved.

The Folch and Bligh Dyer methods are based on protein precipitation with MeOH. Of course, the lipids are more soluble in MeOH/H2O than in H2O, The simultaneous process of extraction with chloroform (usually)aids this. In the Bligh/Dyer technique it is CHCl3/MeOH/H2O in one phase that removes the lipids from the proteins. To get the lipids into a separate chloroform phase one usually adds more chloroform in a second step. The single phase can also be easily broken up by adding more water. This is an interesting use of phase diagrams.

Hello,
I have a question, Is there any way to separate proteins from the lipids in a biological fluid by SPE without any damage to proteins structure?

You should be able to do this using an ion-exchanger.