Area percent purity: difference between revisions
Diff·revision 10 → 11·03:24, 16 Dec 2024
Difference between revision 10 and revision 11 of Area percent purity. 10 lines changed; the page grew by 1,470 bytes.
| Revision 10 — 11:18, 29 Nov 2024 UnitsUrsula (talk) add the cross-link to the compendial chapter 3,599 bytes ±0 | Revision 11 — 03:24, 16 Dec 2024 IsocraticIla (talk) split §Principle from §Practical limitations 5,069 bytes +1,470 | ||
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| 8 | | Typical method = Reverse-phase HPLC with ultraviolet detection | 8 | | Typical method = Reverse-phase HPLC with ultraviolet detection |
| 9 | }} | 9 | }} |
| + | 10 | {{hatnote|For the mass fraction of a vial that is peptide, which is a different quantity, see [[Peptide content]].}} | |
| 10 | 11 | ||
| 11 | '''Area percent purity''' is the integrated area of the principal peak in a chromatogram expressed as a percentage of the total integrated area of all peaks. It is the figure almost always meant when a research-peptide [[Certificate of analysis|certificate]] reports "purity", and it is reported without further qualification often enough that its limitations are worth stating plainly.{{r|usp1503}} | 12 | '''Area percent purity''' is the integrated area of the principal peak in a chromatogram expressed as a percentage of the total integrated area of all peaks. It is the figure almost always meant when a research-peptide [[Certificate of analysis|certificate]] reports "purity", and it is reported without further qualification often enough that its limitations are worth stating plainly.{{r|usp1503}} |
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| 27 | {{note|This is why the method statement on a certificate carries more information than the number does. A figure with a method can be reproduced; a figure without one can only be believed or not.}} | 28 | {{note|This is why the method statement on a certificate carries more information than the number does. A figure with a method can be reproduced; a figure without one can only be believed or not.}} |
| 28 | 29 | ||
| + | 30 | == What area percent cannot see == | |
| + | 31 | Four categories of material are systematically under-represented or absent from an area percent determination. Each of them has been the subject of a documented quality failure in this sector, which is why they are enumerated rather than left implicit.{{r|reports}} | |
| + | 32 | ||
| + | 33 | ; Non-absorbing species : Salts, most sugars and many small-molecule excipients give little or no response at 214 nm. Charged-aerosol or refractive-index detection sees them; ultraviolet detection does not. | |
| + | 34 | ; Non-eluting material : Anything that does not come off the column within the run — strongly retained aggregates, particulate — contributes to neither numerator nor denominator. | |
| + | 35 | ; Co-eluting species : A related substance that shares the principal peak's retention time is counted as principal peak. This is what a peak-purity assessment by diode array or by mass spectrometry is for. | |
| + | 36 | ; Everything that was never dissolved : The determination is performed on the injected solution. Material that did not dissolve is not in it, so an appearance observation on reconstitution is a separate finding from a purity figure and has to be reported separately. | |
| + | 37 | ||
| 29 | == References == | 38 | == References == |
| 30 | {{reflist}} | 39 | {{reflist}} |
| 31 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, "Quality Attributes of Synthetic Peptide Drug Substances" (informational). USP–NF, current revision.</ref> | 40 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, "Quality Attributes of Synthetic Peptide Drug Substances" (informational). USP–NF, current revision.</ref> |
| + | 41 | <ref name="reports">Independent test reports and purchaser submissions held by PeptidePedia, 2024–2026, together with the analytical conditions supplied with them where any were.</ref> | |
| 32 | 42 | ||
| 33 | {{DEFAULTSORT:Area percent purity}} | 43 | {{DEFAULTSORT:Area percent purity}} |