Reference standard: difference between revisions
Diff·revision 20 → 21·03:15, 25 May 2025
Difference between revision 20 and revision 21 of Reference standard. 5 lines changed; the page grew by 652 bytes.
| Revision 20 — 11:39, 3 May 2025 CategoryBot (talk) bot: flag bare reference 4,154 bytes ±0 | Revision 21 — 03:15, 25 May 2025 ExternalLinksEli (talk) clarify that mass spectrometry confirms identity, not purity 4,806 bytes +652 | ||
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| 27 | Identification is stronger still when retention matching is combined with an orthogonal determination — [[Mass spectrometry|mass confirmation]], or a second chromatographic mode with different selectivity. The combination is what pharmacopoeial identification tests specify, and it is a reasonable benchmark for reading any certificate.{{r|usp1503}} | 27 | Identification is stronger still when retention matching is combined with an orthogonal determination — [[Mass spectrometry|mass confirmation]], or a second chromatographic mode with different selectivity. The combination is what pharmacopoeial identification tests specify, and it is a reasonable benchmark for reading any certificate.{{r|usp1503}} |
| 28 | 28 | ||
| + | 29 | == Absence of standards in research supply == | |
| + | 30 | For approved substances a compendial or supplier-qualified standard generally exists, and an independent laboratory can obtain one. For investigational compounds none exists, and identification rests on mass agreement with a calculated value.{{r|usp1503}} | |
| + | 31 | ||
| + | 32 | That distinction is rarely acknowledged in discussion of test results. A purity figure for [[Semaglutide|semaglutide]] rests on an identification that can be anchored to an authenticated material; a purity figure for a compound in phase 3 rests on an identification anchored to arithmetic. Both may be correct; they are not equally well supported. | |
| + | 33 | ||
| 29 | == References == | 34 | == References == |
| 30 | {{reflist}} | 35 | {{reflist}} |