What a certificate of analysis shows
A certificate of analysis (COA) is the document that ties one lot of material to the results of the tests run on it. For a research peptide it should name the compound, the lot, the date and the laboratory, and give each test with its method, its specification and its result.
A peptide COA is a record of what was measured, by which method, on which sample.
What belongs on a peptide certificate of analysis
A complete peptide COA has a line for each field below, each with a unit, a method and, where one applies, a limit.
| Field | What it should state | What to check |
|---|---|---|
| Compound and lot | Compound name and lot number | The lot number matches the lot field on the vial |
| Identity | Mass spectrometry: observed mass, theoretical mass, ionization method (for example ESI or MALDI) | Masses agree within a stated tolerance; spectrum attached |
| Purity | Reverse-phase HPLC: wavelength, column and area-percent result | Chromatogram attached; method stated beside the figure |
| Net peptide content | Mass fraction of the powder that is peptide, with the method named | Not confused with the HPLC purity figure |
| Water | Karl Fischer titration, as % w/w | Unit and method present |
| Counter-ion | Counter-ion identity and content as % w/w (for example trifluoroacetate, acetate or chloride), with the method named, such as ion chromatography or 19F NMR | The salt form is named; trifluoroacetate can remain from cleavage and purification |
| Appearance | Physical description of the powder | Matches the vial contents |
| Date, laboratory, signature | Test date, laboratory name, named signatory | The laboratory can be identified |
Longer treatments: Confirming identity by mass spectrometry, What HPLC purity measures and, for the gap between purity and peptide content, Purity versus net peptide content.
What makes a COA checkable
Checkable means each statement can be tested against something other than the COA itself. Reading a COA comes down to five properties:
- The lot number on the COA matches the vial.
- Methods are stated, not implied: column, wavelength, ionization method.
- The chromatogram and the mass spectrum are attached, not only summarised as numbers.
- The laboratory can be identified by name.
- Results carry units and sit next to their specification limits.
ICH Q6A defines a specification as a list of tests, references to analytical procedures and acceptance criteria, which are numerical limits, ranges or other criteria. It addresses marketing approval of new chemical drug substances and products, so it is cited for the definition only. A result with no limit beside it has no stated criterion to meet.
In-house and third-party testing
Two questions apply to any result: who ran the test, and whether that party is independent of the seller. In-house and independent results differ in what an outside reader can verify. The phrase third-party tested peptides carries information only when the laboratory is named and its report attached.
ISO/IEC 17025 is the international standard for the competence of testing and calibration laboratories, and accreditation bodies use it as the criteria for assessing laboratories. Accreditation, where claimed, is an independent evaluation of the laboratory for specific activities, separate from any one result. A third-party result is still a result for the sample sent, not for every vial.
Where Solara's documentation stands
What this does not establish
- A COA describes the sample tested: a COA for a different lot says nothing about this vial.
- Tests not listed were not run. Water and counter-ion content, for example, are not established by a purity result.
- A result holds at the test date; it does not record how the vial has been stored since.
- ISO/IEC 17025 is described as a standard, not as a statement that any laboratory named on a COA is accredited for the tests it reports.
Questions
What is a certificate of analysis for a peptide?
What should a peptide COA include?
Does a third-party COA cover every vial in a lot?
References
- Specifications: Test Procedures and Acceptance Criteria for New Drug Substances and New Drug Products: Chemical Substances (ICH Q6A). International Council for Harmonisation, 1999.
- About ILAC. International Laboratory Accreditation Cooperation, 2026.
- Roux S et al. Elimination and exchange of trifluoroacetate counter-ion from cationic peptides: a critical evaluation of different approaches. J Pept Sci, 2008.
Every compound on this site is supplied as a lyophilized powder for laboratory research use only. Nothing in this article describes an effect on a person or is a claim about any product.