Practical use of selectivity in ion exchange chromatography

[Coacervate Droplet]

I am trying to understand ion exchange methodology.  The Dow "tech fact" sheet on selectivity for quaternary amine resin as 1 for -OH, 5 for -H2PO4 and 22 for -Cl.

Does that mean that HCl is a better elutant than a solution of Phosphoric acid of equal normality?

Also, To regenerate this column would a strong solution of NaOH be best because it has the lowest selectivity and is easily displaced.  Am I thinking about this correctly?

This is my first post.  I appreciate any dialog on this topic as I need to become proficient with basic applications of ion exchange.  Right now I feel like its a roll of the dice.

 

[BabcockHall]

To give one example of selectivity, suppose you wanted to convert a resin in the chloride form to the acetate form.  You would have to use many column volumes of sodium acetate because of the selectivity difference between the two ions.  But it is cheaper to use even more column volumes of sodium hydroxide, then a couple of column volumes of acetic acid.  The first solution converts the resin into the hydroxide form, and the second solution is deprotonated by the hydroxide ions on the column to create acetate ions.

 

If I understand your question correctly, then I would say that HCl is the better eluant all else held equal.  However, sometimes one has to consider the pH-sensitivities of the column or the compound being eluted in choosing the best conditions.

Edited August 6, 2018 by BabcockHall