Loss on drying: difference between revisions
Diff·revision 10 → 11·02:23, 27 Dec 2024
Difference between revision 10 and revision 11 of Loss on drying. 10 lines changed; the page grew by 613 bytes.
| Revision 10 — 10:53, 12 Dec 2024 LOD_Lorcan (talk) add the ionisation mode to the mass-spectrometry description 2,601 bytes +32 | Revision 11 — 02:23, 27 Dec 2024 KarlFischerKit (talk) de-duplicate a repeated sentence 3,214 bytes +613 | ||
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| 21 | For peptides the conditions must be gentle enough to avoid decomposition. Aggressive drying can cause loss of mass through degradation rather than through evaporation, which inflates the figure and damages the sample; vacuum drying at moderate temperature is the usual compromise.{{r|usp1503}} | 21 | For peptides the conditions must be gentle enough to avoid decomposition. Aggressive drying can cause loss of mass through degradation rather than through evaporation, which inflates the figure and damages the sample; vacuum drying at moderate temperature is the usual compromise.{{r|usp1503}} |
| 22 | 22 | ||
| + | 23 | == Why the distinction from water matters == | |
| + | 24 | Peptide content is calculated by subtracting the non-peptide fractions — water, counterion, residual solvent, inorganic salt — from unity. Each must be determined by a method specific to it, or the subtraction double-counts or under-counts.{{r|usp1503}} | |
| + | 25 | ||
| + | 26 | | Determination | What it captures | | |
| + | 27 | |---|---| | |
| + | 28 | | Loss on drying | Water plus all volatiles, together | | |
| + | 29 | | [[Karl Fischer titration]] | Water only | | |
| + | 30 | | [[Residual solvent]], by gas chromatography | Named organic solvents, individually | | |
| + | 31 | | Counterion assay | [[Trifluoroacetate counterion]] or acetate content | | |
| + | 32 | ||
| 23 | == References == | 33 | == References == |
| 24 | {{reflist}} | 34 | {{reflist}} |