Page 1 of 1
Ion Exchange- Equib times?
Posted: Wed Oct 05, 2011 3:10 pm
by LC_addict
Hi guys! Another quick Q
As you may know, i have no experience with Ion exchange Chromo.
I am using an IC PAK 6um 75cm column with mobile phase of 24mmol HNO3...
If my column is new (especially) how long do you feel i need to equib the column for? It seems my problems have magically fixed, do you think this could be down to not equib'ing for long enough?
Cheers!
Re: Ion Exchange- Equib times?
Posted: Wed Oct 05, 2011 6:39 pm
by tom jupille
Equilibration times can vary considerably, depending on what you are equilibrating from/to.
If your column has strongly bound ions (e.g., divalents) and you are equilibrating with weakly bound ions (e.g., monovalents, and especially H+) then it can take a *very* long time. The only way to be find out in a particular case is to keep injecting standards until things stabilize (or follow the vendors's recommendation!). If you are going the other way (weak to strong), then equilibration can be simply a matter of getting complete wash-out (about 10 column volumes).
Re: Ion Exchange- Equib times?
Posted: Fri Oct 07, 2011 8:27 am
by Markus Laeubli, Metrohm
Equilibration times depend on the intensity of change.
As Tom mentioned going from a strongly retained ion to a weakly retained one will take more time than the other way around. But also large changes in eluent pH may take long time.
In your case the first question is about the type of ion exchanger. Is it a cation or an anion column. In case of a cation column H+ is a weakly bound ion. In case of an anion column nitrate is a medium ion. Also the storage solution of the column is important.
Therefore ther is no direct answer to your question.