Another method to concentrate your protein would be to place it in a
dialysis bag of ~1kD cutoff and place this into dry PEG. This will
serve to draw out the buffer solution while keeping back your protein.
Good luck...Randall C Willis, Publisher, Aliquotes Press
"ALIQUOTES: A Journal of Molecular and Biochemical Humour"
58 Balfour Ave.
M4C 1T6 CANADA
416-813-5933(ph) willis at gandalf.psf.sickkids.on.ca
416-813-5022(fax) rogerb at microsoft.com