Counter-ion
The anion paired with a peptide's basic residues in the isolated salt. Usually trifluoroacetate or acetate. Mass in the vial that is not peptide.
Related terms
- Trifluoroacetic acid (TFA)
- Mobile-phase additive at 0.1 %. Gives excellent peptide peak shape and suppresses electrospray ionisation. Also the most common peptide counter-ion.
- Salt form
- Which counter-ion the compound was isolated as. Trifluoroacetate is 114 Da per site; acetate is 60. At equal purity, acetate vials contain more peptide.
see also Counter-ion · Ion suppression
see also Counter-ion
Where this term appears
The glossary exists to make record pages readable without a chemistry degree. Every technical term on a report resolves here.
- Assay report records — the term appears in result tables, peak tables and provenance blocks
- Method references — where the measurement behind the term is defined
- All 23 glossary terms beginning with C