Pumping strong TFA solution

[Mattias]

Can a standard HPLC pump stand pumping, let's say, 1% TFA in water?

I have problem with evaporation of TFA, which changes my retention times gradually during a sequence. I hope introducing TFA from a third channel on the pump can solve my problem.

[grzesiek]

should be no problem with the pump, but donno what about the mixing, you could get worse baseline because of the problems with mixing

we never had problems with evaporation and retention times changes, how long does the sequence last? is it in aqueous phase or organic phase that evaporation occurs? both?

why does it evaporate?

[Mattias]

The problem is already there from the first injection on onwards. I am running on a Primesep A column, and the TFA is what elutes my compound (not the ACN). So even small differences in TFA concentration over time will show clearly.

I have started to pump in 1% TFA, and baseline is OK and the instrument is not complaining. But I don't know it this will stop the drift yet!

[Vlad Orlovsky]

Mattias,

If you bottles are sealed (tiny hole to compensate for removal of the solvent from the bottle) you should not have problem with evaporation of TFA. We have this problem with ACN (mostly) with Chicago temperature being around 95F and AC units hardly cooling lab to 78F, and we addressed this by sealing all bottles and remaking solutions on Monday.

[Mattias]

Our solvent bottles have only a soft plastic cover (Waters style?). The retention times got perfectly stable when pumping in a stronger TFA solution in channel C.

I guess the evaporation is less important from a strong solution.