how to remove residual TFA from peptides after HPLC

[jiang295]

if use chromtography method, why do not you use SPE method, which will concentrate your peptide rather than dilute.

I am wondering if Uwe's suggestion worked? I usually remove TFA using ion-exchange resin.

[jiang295]

could anyone tell me why TFA is not friendly to cell culture?

if use chromtography method, why do not you use SPE method, which will concentrate your peptide rather than dilute.

I am wondering if Uwe's suggestion worked? I usually remove TFA using ion-exchange resin.

[mbreslav]

I am not sure that such a basic group as guanidine group of arginine will expel TFA during SPE procedure. Also, my understanding is that TFA plays an active role during the partition, and may not be accessible for the counter-ion exchange. But again I would like to hear from people who were able to get rid of the TFA with SPE having an arginine in the backbone of their peptides.

[danko]

Xinshou,

It seams to me that your perception of RP is strictly bound to some kind of a mandatory use of TFA.
Why use TFA when unwanted? I (and other chromatographers) have developed 100s of peptide/protein separation methods without a drop of TFA. Also, I've optimized (altered) many more methods removing TFA from the mobile phase and finding better additives, thus achieving better (especially more selective) separations.
So, although many people think that TFA is the ultimate additive in the RP technique, it actually limits the technique's otherwise various options.

Best Regards

[raearu]

Danko has made a very good point here, although TFA can be very useful both from a peak shape point of view and also to aid solubility TFA is by no means essential for a peptide separation. In fact modern hybrid materials have reduced free silanol concentrations and give much better peak shape with additives such as formic acid than traditional silica based materials. Also there are column technologies based upon charged surface hybrid material which is designed to run with lower ionic strength additives such as formic acid, acetic acid etc and still provide equivalent peak shape that you would expect from working with an ion pairing reagent such as TFA.

worth a look if you want to avoid TFA salts all together

[JasSingh]

Very interesting discussion and appropriate one for the problem we are facing of TFA retention in peptide. We tried to replace using formic acid followed by conversion to acetate.
As mentioned in discussion there are ways to avoid TFA. But what are those ways where in TFA can be avoided specially while using solid phase peptide synthesis.
An elaborative answer is highly appreciated.