Trifluoroacetate counterion: difference between revisions
Diff·revision 15 → 16·02:58, 29 Mar 2025
Difference between revision 15 and revision 16 of Trifluoroacetate counterion. 3 lines changed; the page grew by 410 bytes.
| Revision 15 — 11:28, 9 Mar 2025 TechnicianTeal (talk) add the peptide-content point: area percent alone cannot give a mass 3,489 bytes ±0 | Revision 16 — 02:58, 29 Mar 2025 LOD_Lorcan (talk) fix the anchor on an internal link 3,899 bytes +410 | ||
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| 26 | It is not detected by ordinary [[Reverse-phase HPLC|reverse-phase]] purity determination — it does not absorb usefully at 214 nm and elutes near the void — so a purity figure is entirely unaffected by how much of it is present. This is the clearest single example of why purity and content are not interchangeable. | 26 | It is not detected by ordinary [[Reverse-phase HPLC|reverse-phase]] purity determination — it does not absorb usefully at 214 nm and elutes near the void — so a purity figure is entirely unaffected by how much of it is present. This is the clearest single example of why purity and content are not interchangeable. |
| 27 | 27 | ||
| + | 28 | Nor is it a [[Residual solvent|residual solvent]] in the analytical sense: it is present as a salt rather than as free volatile acid, and a headspace gas-chromatographic method will find little of it. A certificate that reports residual solvents but not counterion has not accounted for this mass.{{r|usp467}} | |
| + | 29 | ||
| 28 | == References == | 30 | == References == |
| 29 | {{reflist}} | 31 | {{reflist}} |
| 30 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, ''Quality Attributes of Synthetic Peptide Drug Substances''.</ref> | 32 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, ''Quality Attributes of Synthetic Peptide Drug Substances''.</ref> |
| 31 | <ref name="roux2008">Roux S, Zékri E, Rousseau B, et al. "Elimination and exchange of trifluoroacetate counter-ion from cationic peptides: a critical evaluation of different approaches." ''Journal of Peptide Science'' 14(3):354–359 (2008). PMID 17994590.</ref> | 33 | <ref name="roux2008">Roux S, Zékri E, Rousseau B, et al. "Elimination and exchange of trifluoroacetate counter-ion from cationic peptides: a critical evaluation of different approaches." ''Journal of Peptide Science'' 14(3):354–359 (2008). PMID 17994590.</ref> |
| + | 34 | <ref name="usp467">United States Pharmacopeia, General Chapter <467>, ''Residual Solvents''.</ref> | |
| 32 | 35 | ||
| 33 | == See also == | 36 | == See also == |