Which Ion-Pair Reagent? TEA, TEAA, TBAA?

[jebus]

Firstly, is TEA as evil as everyone makes out? Just reading some of the equilibration problems makes me wonder if I should bother.

Is there an advantage to using tetrabutyl (or -ethyl) ammonium acetate or some other salt over just triethylamine?

Is the effectiveness of the ion pair reagent (TEA specifically) affected by the pH? I assumed TEA by itself would be a poor Ion-pair reagent.

Thanks for any ideas or opinions.

[tom jupille]

TEA is probably used more for its ability to suppress tailing of basic compounds than for its ion-pairing ability (although it does both). TBA is a more generally used choice for ion-pairing of anions. As you point out, since it's a quat, the ionization is pH-independent.

[jebus]

Thanks, it is as I expected. I just needed to set it straight in my head. I've been looking at this buffer system for so long that it's started not making sense.

If I hada column that had no silanol groups (i.e. PLRP-S), do you think it's worth going on with TEA?

Do you know if the tetraalkylammonium salts are more "well behaved" when it comes to chromatography, baselines, column equilibration etc??

Sorry to labour this issue ... Thanks.

[Uwe Neue]

If you have a modern C18 column based on a high-purity silica, you do not need any TEA any more.

[Chris Pohl]

jebus,

You are correct that with a polymeric reverse phase column you generally don't see the need for the addition of a cation exchange masking reagent such as TEA. In some cases, you might actually see a minor benefit even though a polymeric materials don't have any silanols because their preparation invariably involves a polymeric dispersant (some of which is grafted to the surface of the resident and therefore remains on the surface of the resin even after cleaning) and in some cases the dispersant used has fixed anionic groups which can cause tailing of basic solutes.