Chromatography Forum

I m currently running an IC method on a Dionex ICS-3000 reagent free system and need to remove acetate from my sample due to the fact that it coelutes with my analyte. I'm using conductivity detection with a suppressor. Does anybody know a way to do this?

Flow Rate: 1 mL/min
Gradient: -5 min: 25 mM KOH
6 min: 25 mM KOH
7 min: 70 mM KOH
11 min: 70 mM KOH
Column: Dionex AS11-HC with guard column
Temp 30 C
Injection Volume 15 uL

Hi

Coelution under this very strong elution conditions is not surprising to me. The gradient start at 25mM KOH and increases after 6 minutes in one minute to 70mM (probably step gradient for column flushing). Under this extrem strong conditions i guess Acetate and a lot of other early eluting (or nearly all) analyties will coelute. Before removing acetate (and i'm sure this will not help you to analyze your compound) try the standard gradient (started at 1mM) described in the manual and see how it looks. More info about the AS11-HC could be found here: http://www.dionex.com/en-us/products/columns/ic-rfic/hydroxide-selective-packed/ionpac-as11hc/lp-73257.html.
Best regards and success!