I try to keep commercial information off this bulletin board, but since you
asked...
Our ion-exchange SPE cartridges will meet your needs. Price: US$ 4.50
each. You have the following three options:
1) Anion-exchange: PolyWAX LP (item# SPEWX1203). Elute with a salt step
gradient.
2) Weak cation-exchange: PolyCAT A (item# SPECT1203). You can elute
peptides either with a salt step gradient or with a step to dilute acetic acid
(this uncharges the carboxyl- groups of the coating). However, you should
have at least two basic residues and a free N-terminus to guarantee retention
by WCX.
3) Strong cation-exchange: PolySULFOETHYL A (item# SPESE1203). You have to
use salt for elution (the acetic acid trick won't work in SCX). However, if
you adsorb peptides at a pH < 4, then SCX will retain any peptide with at
least one basic residue).
The cartridges can be reconditioned and reused quite a few times.
Andy Alpert
PolyLC Inc.
9151 Rumsey Road, ste. 180
Columbia, MD 21045 USA
tel: 410-992-5400 FAX: 410-730-8340 e-mail: PolyLC@aol.com