Loss on drying: difference between revisions

Diff·revision 17 → 18·14:19, 24 May 2025

Difference between revision 17 and revision 18 of Loss on drying. 5 lines changed; the page grew by 616 bytes.

Revision 17 — 22:12, 30 Apr 2025 DataTableDunja (talk) move a stray full stop inside the reference 3,765 bytes +30	Revision 18 — 14:19, 24 May 2025 KarlFischerKit (talk) rm the assertion that two laboratories must agree; they need not 4,381 bytes +616
33	A certificate reporting loss on drying ''and'' residual solvents separately is at risk of double counting if both are subtracted, since the solvent contributed to the drying loss. A certificate reporting Karl Fischer water and residual solvents separately is not. This is the practical reason the compendial guidance on peptide quality attributes prefers the specific determinations.{{r\|usp921}}	33	A certificate reporting loss on drying ''and'' residual solvents separately is at risk of double counting if both are subtracted, since the solvent contributed to the drying loss. A certificate reporting Karl Fischer water and residual solvents separately is not. This is the practical reason the compendial guidance on peptide quality attributes prefers the specific determinations.{{r\|usp921}}
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+		35	== Interpreting a figure ==
+		36	Ordinary loss-on-drying figures for lyophilised peptides run from a few per cent to above ten. A high figure is not evidence of a defect: lyophilised peptide cakes are hygroscopic, and a material that has been opened, weighed and resealed will read higher than one analysed immediately.{{r\|usp1503}}
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+		38	A very low figure on a hygroscopic peptide is worth as much attention as a high one, since it implies either aggressive drying or a handling regime a purchaser cannot reproduce. Once a vial is opened in ambient air, water content begins to rise regardless of what the certificate said.
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35	== References ==	40	== References ==
36	{{reflist}}	41	{{reflist}}