Dear Gonzalo Obal,

several substances can migrate between FAMEs and
sterol esters.
It's possible you have isolated alkyl diacylglycerols
(with one or two alkyl groups) and also ester waxes. A
saponification step before the TLC could bring some
information, similarly on the substances separated in
the first migration and separated again in a second
migration step. Any modification in the migration
pattern may throw some light on your problem.
Cordially
Claude Leray









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