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Gradients and Primesep

Posted: Mon Apr 30, 2007 8:17 am
by Mattias
Dear all,

I am running acetonitrile gradients on my Primesep 100 column, and I get reproducible baseline "steps" and other unexpected baseline problems.

(Mobile phase 0.05% TFA in water / 0.05% TFA in acetonitrile. Gradient from 5 - 80% ACN.) If I change to a standard C18 column, I see no baseline problems (but no retention).

I guess this behaviour is due to the ion-exchange properties of the column, but I have no idea why and how to fix it.

Posted: Tue May 01, 2007 9:05 pm
by SIELC_Tech
Mattias,

Do you mind sending me chromatograms and conditions you have tried so far (my eemial is on the bottom)? Is this a method for 5-ASA? Whta else is in the sample. Have you tried isocratic conditions?

regards,

Vlad