What should you check on a peptide CoA?
Use this reading checklist alongside the original report. It is a way to record missing information, not a certification standard or a scoring system. A blank field should prompt a question rather than an invented conclusion.
| Field | What to compare | Question to resolve |
|---|---|---|
| Material and batch | Compound name, modifications, salt form and lot identifiers | Does this report cover the material and batch you are assessing? |
| Sample and laboratory | Sample ID, issuing laboratory and report date | Who tested which sample, and when? |
| Identity | Reported method, expected result and observed result | What evidence supports the stated identity? |
| Purity | Method, chromatogram, integration and result | What does this percentage include and exclude? |
| Content or assay | Amount, units and calculation basis | Was peptide content measured, or is only a nominal quantity stated? |
| Other tests | Results actually listed on the report | Were the attributes relevant to the experiment measured? |
| Acceptance criteria | Specification alongside the measured value | Is this a test result or only a target specification? |
Why are identity, purity and content separate?
Identity concerns what molecule is present; purity concerns the impurities resolved and measured by a particular method; content concerns how much peptide is present on a stated basis. The EMA's synthetic-peptide guideline treats identification, assay and impurities as distinct analytical topics and recommends complementary identification methods. That guideline concerns medicinal-product development; citing it here does not establish that a research supplier complies with it.
A mass result can support identity without quantifying every impurity. Likewise, a chromatogram should not be read as a complete sequence determination. Ask which question the method was designed and shown to answer.
Sources: Guideline on the development and manufacture of synthetic peptides
Is a purity specification the same as a test result?
No. A specification such as 'at least 98%' states an acceptance criterion. A result such as '98.7% by method X' states what was reported for a tested sample. A useful assessment keeps the specification, result and method together. These example numbers are illustrative and are not Zynx batch results.
Record any report limitations and check whether a supplied chart belongs to the same sample as the result table. A signature, logo or polished PDF cannot resolve a mismatch between sample identifiers. If provenance is unclear, ask the named issuer to confirm the report through a contact channel you have independently checked.
Does high HPLC purity prove peptide content or sterility?
No. Peptide content is distinct from chromatographic purity; gross material weight can include water, counterions and other components. A high purity figure alone therefore does not establish the amount of peptide present. Nor is a chromatographic purity result a microbiological test. Read only the measurements the report actually provides.
Sources: Peptide Quick Tips: gross weight, net weight and purity
How does this apply to Zynx documentation?
Use the quality page to see which documents Zynx currently publishes. The website does not operate a batch CoA lookup, and this guide does not imply that a CoA exists for every catalogue entry. For a particular material, ask for the relevant documentation using its compound name and any available batch identifier.
Keep published scientific papers separate from product records. A study about a compound does not identify or certify a supplier's batch. The checklist is intended for laboratory documentation review, not to establish suitability for human use.
Sources and further reading
This guide summarises selected sources. Original publications contain the full methods, results and disclosures; the selection is not a systematic review.
- Guideline on the development and manufacture of synthetic peptides (external)
European Medicines Agency (2025). Sections on identification, assay and impurity control. Medicinal-product guidance, not certification of Zynx or research materials.
- Peptide Quick Tips: gross weight, net weight and purity (external)
Merck / Sigma-Aldrich technical documentation. Explains why net peptide content and peptide purity are distinct.
Continue exploring
- Peptide purity vs content: HPLC and LC-MS explained
- Peptide synthesis and sequencing explained
- Research peptides in Europe: the Zynx approach
Published study records · Quality documentation · Research peptide catalogue