I need some advice.  I'm new to the world of stable isotopes and I'm trying to 
find the best way to extract lipids from cave amphipods.  Cave organisms tend 
to be high in lipids so I'm afraid my carbon values will be skewed.  The method 
I plan on using is as follows:

I will dry my samples and grind them.  I'll place the ground samples in 
centrifuge tubes and add a 2:1 ratio of dichloromethane:methanol with a 
solvent volume approximately 3 to 5 times greater than the sample volume (1g 
sample/3-5 ml solvent).  I'll mix the samples for 30 seconds, wait 30 minutes, 
then centrifuge for 10 minutes.  The supernatant will be pipetted off and given 
time to evaporate.  The lipids will  be left and I'll weigh those.  That will give 
me total mass of lipids.  This process will be repeated until the supernatant is 
clear and colorless.  Then I'll dry those samples again.  

So I'm hoping to get total lipid mass and also lipid free samples to run in the 
mass spec.  Does this sound like it will work?  Anyone have any other 
suggestions.  Thanks.