Understanding a COA: Reading Third-Party HPLC Purity Reports
- A real COA needs a lot number, chromatogram, observed mass and independent lab attribution.
- Missing signatures or recycled chromatograms are major red flags.
- Third-party documentation matters because supplier self-testing is not the same as outside verification.
A Certificate of Analysis (COA) is the single most important document that ships with a research peptide. It is the supplier's auditable evidence that the contents match the label. Researchers should learn to read it line by line.
| COA field | What it confirms | Red flag |
|---|---|---|
| Lot / batch number | Ties the certificate to one synthesis run | Generic or missing lot reference |
| HPLC chromatogram | Shows purity visually, not just as a number | No image, only a typed percentage |
| Observed mass | Confirms the measured compound against theoretical mass | Theoretical mass only |
| Endotoxin result | Adds contamination context | Field omitted entirely |
| Lab signature | Shows accountable third-party validation | No lab identity or sign-off |
What every COA must contain
- Lot / batch number — unique to the synthesis run.
- HPLC purity — typically a percentage (≥98% is the minimum acceptable for research, ≥99% is strong.)
- HPLC chromatogram — visual peak with retention time.
- Mass spectrometry confirmation — observed mass vs theoretical mass.
- Endotoxin testing — LAL assay result in EU/mg.
- Test date and lab signature — must be from an independent third party, not the manufacturer.
Red flags
If a supplier's COA is missing any of the following, treat with suspicion:
- No lab name or signature — this is the most common forgery.
- The same chromatogram across multiple lots — copy-pasted certificates do exist.
- HPLC purity reported without the chromatogram image.
- Theoretical mass shown but no observed mass.
Why third-party matters
Manufacturers testing their own product have an obvious conflict of interest. A genuine third-party lab will accept a request from any researcher to verify their COA against the original report — Synedica routinely facilitates this on request.
The COA is not paperwork. It is the contract between researcher and supplier about what is in the vial. Treat it that way.
Related pages after the COA guide
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Apply the COA checklist while comparing high-demand metabolic kits.
Pair documentation with handling
Quality on paper matters most when storage quality matches it in practice.
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