Clean TFA source or try HFBA?

[DR]

Someone in my lab has had some problems w/ a system peak he has traced to the Trifluoroacetic acid he's been using. He tried another lot and another vendor's material to no avail.

He's looking for 1) suggestions for a supplier of cleaner TFA
2) any experience people may have had switching from TFA to HeptaFluoroButyricAcid - does that change typically mess w/ selectivity a lot in C-18 columns running water/acn gradients?

[Kostas Petritis]

DR,

The one mL vials/ambules of TFA from Sigma is quite clean. TFA that stays long time in their bottles tend to degrade that is why is better to use the one mL ambules. Furthermore, mobile phases of acetonitrile containing TFA would be better not to be used more than a week.

Now about the TFA vs HFBA, yes you might have selectivity differences (depending on your compounds)...