Use of tetrabutylammonium hydrogen sulfate (TBAHS) in LC/MS

[puckeji1]

Is TBAHS in the mobile phase compatible with Q-TOF LC/MS systems? If so, what levels are OK? I found out the hard way that 0.1% diethanolamine is not. Don't want to make the same mistake. Thanks.

[Kostas Petritis]

No it is not. For one it is not volatile and second it is always charged and kind of hydrophobic so it will cause a lot of ion suppression....

I have used alkylamines in the past (i.e. hexyl and heptyl) but they will also suppress your ions in positive ion mode...

[puckeji1]

Thank you Kostas,

The TBAHS was used in the LC method as an ion-pairing reagent. Do you know of any other ion-pairing reagents that could be used instead of TBAHS that would be compatible with the MS system?

[Kostas Petritis]

Hi Jim,

If you are planning to use positive ion mode, I wouldn't use any positive ion-pairing reagents as they are going to at least suppress your signal due to their high proton affinity and in general high hydrophobicity.

In this case it might be worth while to consider columns that offer at the same time reverse phase and cation exchange interactions. There are several posts in this forum about these columns...

If you really want to try ion-pairing reagents, I would go with hexylamine or heptylamine because they are volatile but as I said I do not recommend this pathway...

[Serg]

as alternative, you can derivatize your sample to make it more hydrophobic and thus avoid ion-pair reagent at all.

Regards
Serg