Counterfeit peptide: difference between revisions
Diff·revision 3 → 4·18:40, 22 Dec 2024
Difference between revision 3 and revision 4 of Counterfeit peptide. 5 lines changed; the page grew by 681 bytes.
| Revision 3 — 02:51, 10 Dec 2024 VerifyFirstVida (talk) clarify that a certificate is a claim by its issuer 1,385 bytes ±0 | Revision 4 — 18:40, 22 Dec 2024 BlindSampleBrid (talk) state that the report identifies the sample, not the shipment 2,066 bytes +681 | ||
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| 11 | The determination that detects substitution is identity — [[Mass spectrometry|mass confirmation]], and where available sequence confirmation — not purity. A substituted compound analysed alone will return an excellent [[Area percent purity|area percent]] figure, because it is a pure sample of whatever it actually is.{{r|usp1503}} | 11 | The determination that detects substitution is identity — [[Mass spectrometry|mass confirmation]], and where available sequence confirmation — not purity. A substituted compound analysed alone will return an excellent [[Area percent purity|area percent]] figure, because it is a pure sample of whatever it actually is.{{r|usp1503}} |
| 12 | 12 | ||
| + | 13 | == Substitution == | |
| + | 14 | Substitution replaces the ordered compound with a different one, usually cheaper and often structurally unrelated. Because purity determinations are normalised and identity is frequently not determined, substitution can pass every check a purchaser typically makes.{{r|usp1503}} | |
| + | 15 | ||
| + | 16 | Identity determination is the remedy and is not expensive relative to the purchase. A mass determination compares the observed molecular mass with the calculated one; agreement to within a few daltons excludes most substitutions outright. It does not exclude an isobaric substitution — a different molecule of the same mass — for which sequence-level confirmation is required. | |
| + | 17 | ||
| 13 | == References == | 18 | == References == |
| 14 | {{reflist}} | 19 | {{reflist}} |