What a COA is, and what it isn't
A Certificate of Analysis is a laboratory's record of the tests it ran on a sample from one production lot and the results it got. It documents a specific batch of material on a specific date. It is not a guarantee about every vial a vendor will ever sell, and it says nothing about anything that wasn't tested.
Reports from an independent, third-party lab carry more weight than a manufacturer's own paperwork, because the lab has no stake in the result. The lab's name should be printed on the report, and you should be able to look the lab up.
The header: who, what and when
Before any result, the top of a report tells you what was tested and for whom. These fields are what tie the document to the vial in front of you.
| Field | What it tells you | What to check |
|---|---|---|
| Laboratory | Who ran the analysis | A named, independent lab you can look up |
| Client or "tested for" | Who submitted the sample | Whether the vendor commissioned the test or is passing along a supplier's report |
| Sample name and labeled amount | What the sample was declared to be | Matches the product and the vial size you are looking at |
| Lot or batch number | Which production lot was sampled | Matches the lot printed on your vial |
| Analysis date | When the testing happened | Recent enough to describe the lot actually in stock |
| Report number and verification key | The lab's own reference for the document | Can be looked up on the lab's website |
Purity, by HPLC
High-performance liquid chromatography separates a sample into its components and records each one as a peak. Purity is reported as the main peak's share of the total peak area, as a percentage. A higher figure means fewer related substances, such as truncated or modified sequences left over from synthesis.
Look for the method (HPLC, usually with UV detection) and, ideally, the chromatogram itself. A purity figure with no method and no trace is a number you can't check.
Identity, by mass spectrometry
HPLC tells you how clean a sample is. It doesn't tell you what the main peak actually is. Mass spectrometry, often run as LC-MS, measures the molecular mass of the sample and compares it with the expected mass of the target sequence. A match confirms identity. The two methods are covered side by side in HPLC vs. mass spectrometry.
Net content
Net content, sometimes printed as quantity or assay, is the measured mass of the compound in the vial. It is a different question from purity: a sample can be very pure and still hold a little more or a little less material than the label states. Reports often print it next to the labeled amount so the two can be compared directly. More in Purity vs. net content.
Screening results
Some reports go beyond purity, identity and quantity and screen for contamination:
- Sterility: whether viable microorganisms, or microbial DNA, were detected.
- Endotoxin: bacterial endotoxin, usually by LAL assay under USP <85>, reported in EU/mL.
- Heavy metals: elemental impurities such as lead, arsenic, cadmium and mercury, usually by ICP-MS.
- Adulterant Screen: an immunoassay that checks the sample for undeclared substances.
Treat each of these as tested only if the report shows the row. A report without an endotoxin result tells you nothing about endotoxin. Some labs say so in a note; others just leave the row off. See Endotoxin, sterility and heavy-metal testing.
The verification key
Many independent labs print an access code or QR code on every report. Entering it on the lab's own website brings up the original record, which confirms the document wasn't edited after it left the lab. It takes about a minute and it is the single best check you can run. The steps are in How to verify a peptide COA.
Red flags
- No lot number, or a lot number that doesn't match the vial
- No analysis date, or a date long before the product was stocked
- A purity percentage with no method and no chromatogram
- No identity test of any kind
- One report reused across different vial sizes or lots
- No lab name, or no way to verify the report with the lab
- Screening "passes" in the marketing that don't appear on the report
See the fields on real reports
The Lumina Labs COA Library publishes reports per tested lot, exactly as each lab issued them. To see every field above on an actual certificate, open the LRL-3 RT certificates or the BPC-157 certificates, or browse the full COA Library.
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