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TFA removal service

Choose the appropriate salt form of your peptide to better suit your needs

During solid phase synthesis process, trifluoroacetic acid (TFA) is used to release synthesized peptides from resin and deprotect the lateral chains of amino acids. TFA may also be used during the reversed-phase HPLC purification of peptides. Due to resin cleavage and purification conditions, the resulting peptides contains TFA salts. Anionic TFA counterions interact with the free amine group at the N-terminus as well as side chains of positively charged residues (lysine, histidine, and arginine).

TFA is a strong acid and the presence of TFA-salts counterions in the peptide preparation is detrimental for biological material and ultimately can affect the accuracy and reproducibility of in cellulo and in vivo studies. Peptides supplied by sb-PEPTIDE are lyophilized in the trifluoroacetate format. If TFA-salts counterions would be problematic for your experiment, TF-Acetate salt exchange by another salt form, such as acetate or hydrochloride is required. For biological applications, we recommand to replace TFA-salts counterions by acetate. Indeed, acetic acid (pKa = 4.5) is weaker from both trifluoroacetic acid (pKa ~ 0) and Hydrochloric acid (pKa = -7), and the exchange of TFA-salts by acetate counterions is easier.

Peptide TFA removal

The removal of TF-Acetate salts bound to the peptide is a challenging procedure, since the ion pairing is strong. This service is available as an option, thereby additional charge applies. This includes the required raw material and the peptide loss that occurs during the salt exchange process.

In addition, it is worth noting that bound TFA salts can alter the apparent mass of a peptide as determined by weighing. For this reason, the quantity of our peptides is given in net content rather than Gross Weight generally reported.