---
title: "Trifluoroacetic acid (TFA): identity and role in peptide work"
description: "Trifluoroacetic acid identity data from PubChem and its roles in peptide cleavage, HPLC and salt formation."
canonical: https://www.sablepeptides.co.uk/ref/trifluoroacetic-acid
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# Trifluoroacetic acid (TFA): identity and role in peptide work

## Trifluoroacetic acid (TFA): identity and role in peptide work

*Last updated: 2026-10-10 · Research use only. Not for human or veterinary use.*

## Short answer

Trifluoroacetic acid (TFA, 2,2,2-trifluoroacetic acid, C2HF3O2, 114.02 g/mol, PubChem CID 6422) is a strong, volatile carboxylic acid. In peptide chemistry it cleaves peptides from the resin in Fmoc SPPS, acts as an ion-pairing modifier in RP-HPLC, and remains as the trifluoroacetate counter-ion in many lyophilised peptides. \[1\]

## At a glance

| Term | Definition / specification |
| --- | --- |
| IUPAC name | 2,2,2-trifluoroacetic acid |
| Formula | C2HF3O2 |
| Molecular weight | 114.02 g/mol |
| PubChem CID | 6422 |
| Uses in peptide work | Resin cleavage, HPLC ion pairing, salt counter-ion |
| Trifluoroacetate anion | CF3COO−, ~113 Da, counted in salt formula weight |

## Ion pairing

At a typical literature level of about 0.1% in HPLC mobile phases \[2\], TFA protonates basic groups and pairs with them, sharpening peaks.

## Residual counter-ion

Because the anion binds to positively charged residues, it persists through lyophilisation and contributes to gross weight; it can be exchanged for acetate.

## FAQ

**Is TFA the same as trifluoroacetate?**

TFA is the acid; trifluoroacetate is its anion, the form bound in peptide salts.

**Can residual TFA be removed?**

Largely, by counter-ion exchange; see /ref/tfa-vs-acetate-salts.

## Related reference pages

-   [TFA vs acetate salts of peptides](/ref/tfa-vs-acetate-salts)
-   [Solid-phase peptide synthesis (SPPS)](/ref/solid-phase-peptide-synthesis)
-   [What HPLC purity means for a research peptide](/ref/hplc-purity)
-   [Reference index](/ref)

## Sources

1.  Roux S et al. Elimination and exchange of trifluoroacetate counter-ion from cationic peptides: a critical evaluation of different approaches. *J Pept Sci*. 2008. PMID: [18035848](https://pubmed.ncbi.nlm.nih.gov/18035848/)
2.  Hansen PR et al. Fmoc Solid-Phase Peptide Synthesis. *Methods Mol Biol*. 2015. PMID: [26424261](https://pubmed.ncbi.nlm.nih.gov/26424261/)
3.  PubChem. Trifluoroacetic acid (C2HF3O2, 114.02 g/mol). CID [6422](https://pubchem.ncbi.nlm.nih.gov/compound/6422)

\---

Research use only. This page describes laboratory chemistry and analytical methods. It is not advice on any use in people or animals.

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## Cite this

Research use only. Not for consumption. No health claims.

Plain

Sable Peptides. (2026). trifluoroacetic-acid. UK Research Peptide Reference. Retrieved 11 October 2026, from https://www.sablepeptides.co.uk/ref/trifluoroacetic-acid

APA

Sable Peptides. (2026, October 11). \*trifluoroacetic-acid\*. UK Research Peptide Reference. https://www.sablepeptides.co.uk/ref/trifluoroacetic-acid

BibTeX

@misc{sable\_trifluoroacetic-acid\_2026,
  author = {{Sable Peptides}},
  title = {{trifluoroacetic-acid}},
  year = {2026},
  howpublished = {\\url{https://www.sablepeptides.co.uk/ref/trifluoroacetic-acid}},
  note = {Accessed 11 October 2026. CC BY 4.0}
}

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Date modified: 2026-10-16

Reviewed by Sable Peptides editorial team · 14 October 2026 · [Editorial policy](/editorial-policy)