A Certificate of Analysis is only as useful as the reader's ability to interrogate it. This article provides a practical checklist for reviewing a peptide COA against the physical product and against reasonable analytical expectations. Nothing here suggests that any particular supplier is untrustworthy; it is simply a rigorous evaluation framework.
The verification checklist
Work through each item below when a peptide arrives. If any item cannot be answered from the documentation, note it and, where appropriate, request clarification.
1. Product name
Does the product name on the COA match the vial label exactly? Check spelling, dosage designation (e.g. "10 mg"), and any code or trade name. A mismatch — even a minor one — is worth clarifying before use.
2. Batch/lot number
Does the COA carry a batch or lot number, and does it match the number on the vial label and outer packaging? A COA without a lot number cannot be tied to the material shipped. See why batch-specific peptide COAs matter.
3. Testing date
Is a testing date shown? Is it plausible — after the batch's manufacture date, and not so old that intervening storage might have affected the material?
4. Laboratory information
Is the issuing laboratory named? Is it identified as the supplier's in-house QC lab or as an independent third party? Either can be legitimate; both should be transparent. Where a third-party lab is named, a quick search should confirm it exists.
5. Analytical method — HPLC
Does the HPLC section state the column (make, model, dimensions, particle size), the mobile-phase composition and gradient, flow rate, detection wavelength and run time? Details of the method allow the result to be evaluated in context. See what is HPLC peptide testing for what these parameters mean.
6. HPLC result
Is the purity value stated with an appropriate number of significant figures, alongside the corresponding chromatogram? A single number without a chromatogram is difficult to evaluate.
7. LC-MS result
Where the peptide's identity has been confirmed by mass spectrometry, is the observed molecular mass shown alongside the theoretical mass, with an explicit mass error? Is the ionisation source disclosed? See LC-MS peptide testing explained.
8. Supporting chromatograms and spectra
Are chromatograms and mass spectra included as images? A COA that quotes results without visual evidence forces the reader to accept the values on trust. Rigorous documentation shows the underlying data.
9. Consistency between documentation and product information
Do the product name, dosage and description on the COA match what you ordered and what appears on the vial? Any inconsistency — different peptide name, different weight, different sequence — is a signal to pause and clarify before use.
10. Signatures and authorisation
Is the COA signed, initialled or otherwise authorised? Formal authorisation is a marker of a controlled QC process.
A worked example
At Peptovia Research, our Certificate of Analysis page shows examples of third-party COAs issued for specific batches, each carrying a lot number, HPLC purity value, LC-MS-confirmed mass, and the issuing laboratory's reference. Reviewing these examples against the checklist above is a useful exercise for anyone building the habit.
What to do when something is missing
Not every COA meets every checklist item. A missing item is not automatic evidence of a problem, but it is a reason to ask. Contact the supplier, cite the specific field that is unclear or missing, and request supplementary documentation. A supplier committed to transparency will respond constructively.
A note on tone
This checklist is not a way to catch suppliers out. It is a professional habit that protects the researcher, ensures data integrity, and encourages consistent documentation standards across the industry. Suppliers with good analytical practices will welcome informed questions from their customers.
Conclusion
Verifying a COA is a small habit that pays dividends over the course of a research programme. It takes a few minutes on receipt of each shipment, it produces a documented paper trail, and it flags problems before they become experimental variables. Combined with how to read a peptide COA, this checklist gives researchers a defensible process for evaluating the documentation attached to every batch of peptide material.
Research Use Only — This article is provided for research and educational purposes.