Area percent purity: difference between revisions
Diff·revision 24 → 25·07:01, 20 Sep 2025
Difference between revision 24 and revision 25 of Area percent purity. 4 lines changed; the page grew by 1,157 bytes.
| Revision 24 — 08:35, 28 Aug 2025 SatietySunniva (talk) clarify that mass spectrometry confirms identity, not purity 7,380 bytes ±0 | Revision 25 — 07:01, 20 Sep 2025 CategoryBot (talk) bot: sort category members 8,537 bytes +1,157 | ||
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| 55 | First, '''report the method with the figure''': column chemistry, gradient, flow rate, detection wavelength, injection volume. Second, '''itemise related substances individually''' rather than reporting a single aggregate impurity figure — an aggregate conceals whether one impurity is at 0.9% or nine are at 0.1%, which are different situations. Third, '''state the integration threshold''', because it determines what was counted at all. | 55 | First, '''report the method with the figure''': column chemistry, gradient, flow rate, detection wavelength, injection volume. Second, '''itemise related substances individually''' rather than reporting a single aggregate impurity figure — an aggregate conceals whether one impurity is at 0.9% or nine are at 0.1%, which are different situations. Third, '''state the integration threshold''', because it determines what was counted at all. |
| 56 | 56 | ||
| + | 57 | Where a purchaser is comparing an independently obtained figure with a certificate figure, a difference smaller than the repeatability of the method is not a finding. Repeatability for a well-behaved peptide on a validated method is typically a few tenths of a percentage point across replicate injections; differences of that size between two laboratories are expected.{{r|iso17025}}{{r|ichq2}} Repeatability, intermediate precision and reproducibility are separate parameters, and only the first is measured within one laboratory on one day. Larger differences have ordinary methodological explanations before they have any other kind, and the article on [[Third-party testing]] sets out how to distinguish them. | |
| + | 58 | ||
| 57 | == References == | 59 | == References == |
| 58 | {{reflist}} | 60 | {{reflist}} |
| 59 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, "Quality Attributes of Synthetic Peptide Drug Substances" (informational). USP–NF, current revision.</ref> | 61 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, "Quality Attributes of Synthetic Peptide Drug Substances" (informational). USP–NF, current revision.</ref> |
| + | 62 | <ref name="iso17025">ISO/IEC 17025:2017, ''General requirements for the competence of testing and calibration laboratories''. International Organization for Standardization.</ref> | |
| 60 | <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> | 63 | <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> |
| + | 64 | <ref name="ichq2">International Council for Harmonisation, ''Q2(R2): Validation of Analytical Procedures''. Distinguishes repeatability, intermediate precision and reproducibility, which are frequently conflated when two figures for one lot are compared.</ref> | |
| 61 | 65 | ||
| 62 | == Further reading == | 66 | == Further reading == |