COA Analysis & Interpretation
A Certificate of Analysis is only as good as the answer to one question: who produced it, and does it belong to your batch?
The COA trust ladder
| Level | What it is | Actual value |
|---|---|---|
| Vendor's own "COA" | PDF generated by the vendor for marketing | Near zero — self-reported |
| Manufacturer COA | From the synthesis facility | Moderate — confirms source claims, but you're trusting the maker |
| Independent lab COA, batch-matched | Third-party test of the batch you receive | High — the only level that tests your vial |
| Independent + your own retest | You (or a group buy) send a vial to a lab yourself | Highest — zero conflict of interest |
Anatomy of a real HPLC report
- Chromatogram: the actual trace with a dominant main peak. A single clean peak at the right retention time is what you want to see.
- Purity %: usually 97–99%+ for quality material. Compare the number to the trace — the trace is harder to fake than the number.
- Method parameters: column, gradient, wavelength. Real reports include them; vague reports hide them.
- Batch number & date: must match the vial batch and be recent enough to mean something.
- Sample description: what exactly was tested — "peptide X, batch Y" not "product Z, all batches."
What purity testing does NOT tell you
HPLC purity ≠ identity, ≠ sterility, ≠ endotoxin level, ≠ biological activity. A 99% pure sample of the wrong peptide is still the wrong peptide. Identity requires mass spectrometry; sterility and endotoxin require their own assays. See Even a Real COA Isn't Enough.
Red flags in a COA
- No batch number, or a generic "all batches" statement
- Identical COA reused across products (check dates and batch fields)
- Lab name you cannot verify independently — search the lab, call it
- Purity claims with no chromatogram attached
- Typos in peptide nomenclature (a sign of template reuse)
Best third-party testing labs
The labs below test peptides without a commercial relationship to vendors. We don't take placements — these are the facilities that consistently appear in verified community retesting because they accept individual submissions:
- Janoshik Analytical — widely used for independent peptide retesting (HPLC + MS + endotoxin).
- MZ Biolabs — full-service analytical lab accepting direct submissions.
- Peptide Test (peptidetest.com) — dedicated third-party peptide testing service.
Always check current pricing/requirements directly with the lab before sending anything. Group buys split the cost of a full panel.