Can you put Ion Pairing Reagents in pH 9 (or so) buffer? This is a new venture for me. Are the alkyl sulphonates fine? TEA is not part of my buffer at this point.

I don't see a reason why not, just try it, and if it works, you have a method, test robustness, and if you still have a method, you can validate it.

Ion pair will definitely work at high pH. You don't have to worry about hydrolytic stability of alkyl sulfonates. The one thing to keep in mind is that the solubility of alkyl sulfonates is quite pH dependent with solubility at a minimum at high pH. This also depends on the cation with lithium salts being most soluble. On the other hand, in organic solvents the maximum solubility is achieved with the most polarizable cation (cesium) with amine cations as good alternatives for improving solubility in solvents.

Dear Wanda!
I agree with Chris -- your idea sounds reasonable, so I`ll be grateful to you if you present some information about your objects and your study.
As for me I think silicagel based packing wont stand high pH, you`ll only wastin you time. But polymeric phases are also not acceptible! they dont posess "surface" for adsorption of modifiers! So thats a problem to think of. I heard that well endcapped phases can work at ph 8-9, try to find article in Journal Chrom.A by Guyshon (I don`t remember correct spelling).
Waitin for reply,
Constantine

Constantine,

I agree with you that silica gel generally won't exhibit long life at high pH (although there are a couple of types which which exhibit improved life at high pH compared to conventional materials) but it is not true that polymeric phases don't possess "surface" for absorption of modifiers. Dionex (not to mention Hamilton and Polymer Laboratories) sell a polymeric column (the Dionex column is: MPIC NS1) that is routinely operated with ion pair reagents. In fact, polymeric columns generally exhibit more retention in the ion pair mode than silica based reversed phase columns.

Chris,
I`ll be very grateful if you present some material on application of mobile phases with ion-pair reagents with Hamilton PSDVB phases. Mea culpa, I was anaware of this property of such packings. My email is present.
Best regards,
Constantine

Nowadays, there are several packings available that are hard like silica and stable at high pH. One is the XTerra packing from Waters, the other one is a packing from Agilent, whose name I do not remember at the moment. It is prepared with a silanization reagent that has a multivalent ligand. These packings can be used to pH 11. Otherwise, I bet that they work well in ion-pair, because they are C18-types.

Constantine,

There's quite a bit of literature on the ability to use porous polymers for ion pair. Here's one example where it's being used for the analysis of Cr III and Cr VI: http://link.springer-ny.com/link/service/journals/00216/bibs/5351007/53510604.htm

Ion pair means that you have one negative ion on the ion pair reagent and one positive ion on the analyte so that to form the ion pair.
Most basic compounds at pH>8 aren't charged enough, i mean that the molar ratio between the ucharged and the charged form of the analyte is >80, so that to form the ion pair thus the ion pair reagent won't effectively. I suggest that, if you want to work with ion pair reagents at high pH values then your analyte must have an acidic character so that to use tetrabutilamonium bromide as ion pair reagent.
Please, do correct me if i am wrong.
Thank you for the hosting

Chempara

This depends on the basicity of the ionizable group. Aromatic amines require lower pH to get them into cationic form. But I get your point. If you want to separate basic solutes at via ion pair the pH should be low enough to get the analyte in the ionized state. The reason to go to high pH is for use of the ion suppression mode of reversed phase retention. In this case, there would be no need for an ion pair reagent since the species are neutral. I have a hard time seeing why one would want to try ion pair of cationic species at high pH. Ion pair separations of cationic species are normally done at pH less than 7.

Chris, thank you for information)))
As for your reply to chempara -- "This depends on the basicity of the ionizable group. " This method should work if the basicity is very high about 10-11. It may posses some advances: selectivity, .. et cetera)))