Residual solvent: difference between revisions

Diff·revision 17 → 18·14:51, 16 Jul 2025

Difference between revision 17 and revision 18 of Residual solvent. 5 lines changed; the page grew by 658 bytes.

Revision 17 — 01:30, 23 Jun 2025 CategoryBot (talk) bot: sort category members 4,161 bytes ±0	Revision 18 — 14:51, 16 Jul 2025 Chromatokid (talk) split §Principle from §Practical limitations 4,819 bytes +658
31	Trifluoroacetic acid is a special case. It is used in both cleavage and purification, is not always covered by a standard residual-solvent method, and in the isolated peptide is present largely as the [[Trifluoroacetate counterion\|trifluoroacetate counterion]] rather than as free acid. The counterion is determined by a separate ion-chromatographic or spectroscopic method.{{r\|usp1503}}	31	Trifluoroacetic acid is a special case. It is used in both cleavage and purification, is not always covered by a standard residual-solvent method, and in the isolated peptide is present largely as the [[Trifluoroacetate counterion\|trifluoroacetate counterion]] rather than as free acid. The counterion is determined by a separate ion-chromatographic or spectroscopic method.{{r\|usp1503}}
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+		33	== Relevance to peptide certificates ==
+		34	Residual solvent contributes mass that is not peptide, so it enters the [[Peptide content\|content]] calculation alongside water and counterion. Where content is determined directly by amino acid analysis or by quantitative nitrogen determination this is handled implicitly; where content is inferred by subtraction it must be handled explicitly.{{r\|usp1503}}
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+		36	Certificates in research-chemical supply report residual solvents less often than they report purity or water. Its absence is a gap in the document rather than evidence about the material, and the correct inference is that the attribute is uncharacterised.
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33	== References ==	38	== References ==
34	{{reflist}}	39	{{reflist}}