Peptide content: difference between revisions
Diff·revision 18 → 19·15:54, 30 Jun 2025
Difference between revision 18 and revision 19 of Peptide content. 9 lines changed; the page grew by 1,206 bytes.
| Revision 18 — 02:41, 8 Jun 2025 ColumnOvenCoy (talk) expand §Why it is so often absent 6,925 bytes +27 | Revision 19 — 15:54, 30 Jun 2025 LiraLotte (talk) correct the resolution formula — the denominator is the sum of the widths 8,131 bytes +1,206 | ||
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| 53 | Both statements are true of the same vial. Which one a purchaser needs depends on what the nominal fill was specified to mean, and the honest position is that on unregulated material this is frequently not specified at all: a "5 mg" vial may be filled to 5 mg of gross solid or to 5 mg of peptide, and the two differ by exactly the content figure. '''Where a certificate reports content, it is worth asking which convention the fill statement follows.'''{{r|usp1503}} | 53 | Both statements are true of the same vial. Which one a purchaser needs depends on what the nominal fill was specified to mean, and the honest position is that on unregulated material this is frequently not specified at all: a "5 mg" vial may be filled to 5 mg of gross solid or to 5 mg of peptide, and the two differ by exactly the content figure. '''Where a certificate reports content, it is worth asking which convention the fill statement follows.'''{{r|usp1503}} |
| 54 | 54 | ||
| + | 55 | == Why it is so often absent == | |
| + | 56 | Content appears on a minority of the certificates described in reports reaching this wiki, and its absence has a straightforward explanation that is not a moral one: purity by chromatography is fast, cheap and produces an impressive number, while content requires at least two further determinations and produces a number that looks worse.{{r|reports}} | |
| + | 57 | ||
| + | 58 | That asymmetry is why this wiki records, on each supplier article, whether content is supplied as standard or on request, and why [[Certificate of analysis]] lists the four items a purchaser should ask for. A supplier that holds the water and counterion determinations in its own records can supply a content figure against a named lot without repeating any laboratory work, and the request costs nothing but the asking. | |
| + | 59 | ||
| 55 | == References == | 60 | == References == |
| 56 | {{reflist}} | 61 | {{reflist}} |
| 57 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, "Quality Attributes of Synthetic Peptide Drug Substances" (informational). USP–NF, current revision. Sets out peptide content as an attribute distinct from chromatographic purity.</ref> | 62 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, "Quality Attributes of Synthetic Peptide Drug Substances" (informational). USP–NF, current revision. Sets out peptide content as an attribute distinct from chromatographic purity.</ref> |
| 58 | <ref name="iso17025">ISO/IEC 17025:2017, ''General requirements for the competence of testing and calibration laboratories''. International Organization for Standardization.</ref> | 63 | <ref name="iso17025">ISO/IEC 17025:2017, ''General requirements for the competence of testing and calibration laboratories''. International Organization for Standardization.</ref> |
| + | 64 | <ref name="reports">Certificates and independent reports submitted to PeptidePedia by purchasers, 2024–2026. A self-selected sample; the absence of a determination from a submitted document does not establish its absence from the issuer's records.</ref> | |
| 59 | <ref name="ichq3c">International Council for Harmonisation, ''Q3C: Impurities — Guideline for Residual Solvents''. Classifies solvents by toxicity and sets concentration limits; the acetonitrile used in preparative purification falls in the second class.</ref> | 65 | <ref name="ichq3c">International Council for Harmonisation, ''Q3C: Impurities — Guideline for Residual Solvents''. Classifies solvents by toxicity and sets concentration limits; the acetonitrile used in preparative purification falls in the second class.</ref> |
| + | 66 | ||
| + | 67 | == Further reading == | |
| + | 68 | * [[Project:Manual of style]] — the unit and significant-figure conventions the worked examples on this page follow. | |
| 60 | 69 | ||
| 61 | == See also == | 70 | == See also == |