182 3 Lipids
(3.40a)(3.40b)(3.41)(3.42)Phytosphingolipids are isolated from soya and
peanuts (cf. Formula 3.42).
3.4.2 Analysis...............................................
3.4.2.1 Extraction,RemovalofNonlipids..........................
A solvent mixture of chloroform/methanol
(2+1v/v) is suitable for a quantitative extrac-
tion of lipids. Addition of a small amount of
BHA (cf. 3.7.3.2.2) is recommended for the
stabilization of lipids against autoxidation.
Nonlipid impurities were earlier removed by
shaking the extracts with a special salt solution
under rather demanding conditions. An improved
procedure, by which emulsion formation is
avoided, is based on column chromatography
with dextran gels.
3.4.2.2 Separation and Identification of Classes of Components.......
Isolated and purified lipids can be separated
into classes by thin layer chromatography using
developing solvents of different polarity. Fig-
ure 3.12 shows an example of the separation of
neutral and polar lipids. Identification of polar
lipids is based on using spraying reagents which
react on the plates with the polar moiety of
the lipid molecules. For example, phosphoric
acid is identified by the molybdenum-blue
reaction, monosaccharides by orcinol-FeCl 3 ,
choline by bismuth iodide (Dragendorffreagent),
ethanolamine and serine by the ninhydrin reac-
tion, and sphingosine by a chlorine-benzidine
reagent.
When sufficient material is available, it is advis-
able to perform a preliminary separation of lipids
by column chromatography on magnesium sili-