Ken
Thank you for your question.
While it "makes sense" to try and get something more hydrophobic for RPC of
polar molecules which do not retain sufficiently, RPC of peptides is
already done on a fairly heavily covered surface to keep the interactions
with any silanols to a minimum. Hence, it is with diminishing returns that
we trudge down this path to the snare of disappointment. The conventional
approach would be to get more surface area to increase the capacity factor,
since it would give you more carbon per square meter of pore volume.
However, there are alternatives to consider.
Adverse to hydophilic interaction chromatography (HILIC) though some may
be, it does work, it works much less expensively than what you are
proposing, it is available in many formats and it is designed for
hydropilic molecules! You can have a volatile mobile phase and it can
remove detergents that may be complicating your work. Unless there is a
problem with starting your gradient at 90% MeCN in 15mM formate buffer and
running a few steps to 30% MeCN, I would consider this approach as an
alternative.
If it is Tips you are interested in, there are several chemistries
available for this technique from 1-10 ul on up to 250 ul volume. I would
recommend a HILIC-SEA product over the Stylus ProTip only for the added
surface area and secondary mechanisms it offers, though either should work.
More data on the molecule would make the choice easier.
Look at HTTP://world.std.com/~nestgrp/protocols/protocol.html for choices
and a link to part numbers if you are interested in pursuing this.
Hope you are successful.
Sincerely,
Amos
Amos Heckendorf (nestgrp@world.std.com)
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