Hi,

A lipid mixture (all different types of lipids) is soluble
in chloroform mixed with either methanol or isopropanol, the
ratio doesn't have to be exact, but most people seem to use
2:1 (ie. two parts chloroform to one part methanol).

If you are interested in which classes of lipids are most
soluble in which solvents types, the following table comes
from the list of solvents used to fractionate lipid classes
from solid phase extraction columns (aminopropyl-, or diol-
bonded columns) [method adapted from Kaluzny 1985].

Whole lipids placed on first column
Neutral lipids Chloroform: Isopropanol [2:1]

(neutral lipid fraction is dried and redissolved in hexane, then
placed onto second column >>> )

(meanwhile the first column is extracted with...)
Free fatty acids 2% acetic acid in diethyl ether
Phospholipids Methanol

( >>> neutral lipid on second column is then fractionated)
Cholesteryl esters Hexane
Triacylglycerols Hexane: dichloromethane: diethyl ether
[89 : 10 : 1]
Cholesterol Hexane : Ethyl acetate [95 : 5]
Diacylglycerols Hexane : Ethyl acetate [85 :15]
Monacylglycerols Chloroform : Methanol [2:1]

Neutral lipids are more soluble in Chloroform: isopropanol than they
are in pure hexane, but for this extraction procedure they are
required to be in hexane.

For individual compounds, you can check the Sigma website for
solubility information (they give amounts as well, eg. "1mg / 10ml
produces a clear solution") and also the Merck Index.

The second question of solubility of lipids within lipids is
something I don't have much experience of, and can be complicated
by the different types of fatty acids making up the compound.

For example, butterfat triglycerides contain more saturated fatty
acids compared with olive oil triglycerides - thus in this case,
triglycerides are not particularly soluble in triglycerides !
Until you heat them.

I can't imagine that triglycerides are soluble in cholesterol
unless the triglycerides had very short chains (the longer chain
ones behave as very non-polar, whereas cholesterol is more
amphipathic). I'm really not sure though.

For more information, contact some of the lipid companies (some
contact details are available in the Bookmarks page at the
website) as they routinely prepare and purify lipids.

Hope that helps
Jo
http://groups.yahoo.com/group/lipids/links