ORGLIST members:

A seemingly simple question.  Our group recently purchased our first LC, and
we have been using reverse phase columns to do our analytical separations,
such as routine reaction monitoring.  We are now considering the purchase of
a preparative column for the system to speed up actual product isolation on
the gram scale.  However, when we consider product isolation from the column
fractions, it sounds like it could be messy.  We're using MeCN/water
mixtures for the analytical, and sometimes phosphate buffers.  Is there a
generic, generally applied technique to isolate your compound from these
mixtures?  It seems like the best approach would be to strip the organic,
and then extract the compound from the aqueous residue into another solvent.
However, this looks like an invitation to yield loss, since it's a lot more
manipulation (strip, extract, separate, dry, strip again) than isolating
ones compound from a straight phase column and just stripping the solvent.
We really like reverse phase for analytical, and don't want to go back to
straight phase to make the preparative scale separations easier, since we'd
have to reoptimize all of our solvents and conditions.

Is there any good folk art out there regarding a nice general procedure to
deal with fractions from preparative reverse phase LC?

thanks,

Joe Bozell
Senior Chemist
National Renewable Energy Lab
Golden, CO  USA
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