Dilute the TFA:scavenger mix with any of the following at a 1:10 ratio (1 part TFA mix).
diethyl ether
or
tert-butyl metyl ether
or
ethyl acetate:diethyl ether (2:1)...especially good with thioanisole
Place this solution on dry ice for 20 minutes then centrifuge at 2000 rpm for 15 minutes to get a nice white pellet. resuspend in minimal TFA and repeat until the only smell is the extraction solvent.
Additionally, you can follow this up with Sep-paks to get a crude purification. However, I have found it most cost effective overall to spend as much time as needed to ensure that couplings are as complete as possible and acetylate as needed. The bulk of your time and money is in purification (solvent purchase/disposal), folding (i.e. disulfides) and characterization of the peptide. Don't skimp up front and your job is easier.
Hank Wolfe
Nycomed Amersham
Philadelphia Pa