Acceptable ion pairing reagent for use with LC/MS?

[adam]

Hello

I wanted to ask: Is there an ion pairing reagent that is OK to use with LC/MS? Meaning it does not cause suppression.

I know that TFA is very problematic, but I'm wondering if there may be ion pairing reagents that are OK to use.

In other words, what we are looking for is something that gives the desirable ion pairing behavior in the HPLC column, but does not show the undesirable ion pairing behavior in the mass spec. Maybe it's Pie in the Sky, but I wanted to ask.

Any thoughts or suggestions?
Much Appreciated

[Klaus I.]

When negative ionization is not really needed for me personally TFA is the preferred agent. I have the impression that many people would consider the mechanism of TFA not as a clearly ion-pair mechanism. Nevertheless this only an academic question and I usually avoid this discussions ;o)

My hands-on experience is that using small 1mL ampullae instead of 100 mL bottles is recommended. Please keep in mind that long-term use of TFA in your lc-system may contaminate it permanently and negative mode is therefore unusable or only possible with limited sensitivity. Unfortunately I have no experience with that since I usually don’t use the negative mode.

Regards
Klaus

[mckrause]

I agree with Klaus; TFA is not really an ion-pairing reagent.

With all of the advances made in HILIC and other column technologies do you really need to use an ion-pairing reagent? Our experience has been that we've been able to get around almost all of the ion-pairing separation requirements by changing chromatography. If you can avoid them your MS will be happier.

[stdev]

That s an interesting question... In my opinion you should avoid the combination of ion pair and mass spectrometry. You can try hilic instead, a cyano column, a bare silica column or even derivatisation to reduce the polarity of your analyte...

Hope it helps!

[Kenn]

Hello

I wanted to ask: Is there an ion pairing reagent that is OK to use with LC/MS? Meaning it does not cause suppression.

I know that TFA is very problematic, but I'm wondering if there may be ion pairing reagents that are OK to use.

In other words, what we are looking for is something that gives the desirable ion pairing behavior in the HPLC column, but does not show the undesirable ion pairing behavior in the mass spec. Maybe it's Pie in the Sky, but I wanted to ask.

Any thoughts or suggestions?
Much Appreciated

Hepto fluro butiric acid, HFBA.