Area percent purity: difference between revisions
Diff·revision 3 → 4·16:08, 13 Sep 2024
Difference between revision 3 and revision 4 of Area percent purity. 5 lines changed; the page grew by 767 bytes.
| Revision 3 — 13:33, 6 Sep 2024 TechnicianTeal (talk) add the peptide-content point: area percent alone cannot give a mass 1,841 bytes +33 | Revision 4 — 16:08, 13 Sep 2024 MassSpecMarv (talk) rm the claim that the method is stability-indicating without a forced-degradation study 2,608 bytes +767 | ||
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| 12 | Four choices in that description change the answer, and none of them is usually stated on a certificate: | 12 | Four choices in that description change the answer, and none of them is usually stated on a certificate: |
| 13 | 13 | ||
| + | 14 | * '''The gradient.''' A shallow gradient resolves species that a steep one runs together. Two laboratories can obtain two honest and different figures for one vial by choosing differently here. | |
| + | 15 | * '''The detection wavelength.''' At 214 nm the peptide bond dominates and most peptide-related impurities are seen. At 280 nm only aromatic residues respond, and a related substance without one is invisible. | |
| + | 16 | * '''The integration rule.''' Valley-to-valley and drop-line integration assign the area under an unresolved shoulder differently, and the difference lands entirely on the principal peak. | |
| + | 17 | * '''The integration threshold.''' Peaks below the threshold are not counted at all, so raising it raises the reported purity without any change to the material.{{r|usp1503}} | |
| + | 18 | ||
| 14 | == References == | 19 | == References == |
| 15 | {{reflist}} | 20 | {{reflist}} |