Electroeluting a protein from a gel, with a buffer containing SDS
will give you a solution with protein and SDS. You can freeze dry this
in a small tube, and then rinse/wash it a few times with 90% ethanol. This
gets SDS, coomassie-blue, dithiothreitol, and even tris buffer I think, out
of your protein.
Of course its dead, denatured, and spread all over the walls of your
tube in a film. But that's the way you want it if your'e doing vapor phase
HCl hydrolysis for amino acid analysis (PicoTag).
Maybe this is useful for what you're doing.... Good Luck
Steve Driska