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How to Read a Peptide Certificate of Analysis (COA)
A certificate of analysis (COA) is a lab report for one batch of a product. A good one tells you what is in the vial, how much, and how clean it is. A bad one is a PDF with a big number on it. This guide shows you how to tell the difference.
What a COA is, and what it is not
A COA reports the results of specific tests on a specific batch, run by a named lab on a named date. It only describes the batch it was run on. A COA for last year’s batch says nothing about the vial in front of you.
A COA is not a safety approval. Even regulated pharmacies must hold a valid COA for every bulk ingredient they compound with, and that is a minimum, not a guarantee. For unapproved research peptides, the COA is often the only quality information you will get, so it is worth reading properly.
The tests, one by one
| Test | What it answers | What a result looks like |
|---|---|---|
| HPLC purity | How much of what the detector sees is the main compound? | A percentage, such as 99.1%, with a chromatogram showing one dominant peak |
| Mass spectrometry (LC-MS or MS) | Is the main compound actually the right molecule? | A measured mass that matches the expected molecular weight |
| Quantity / fill | How many milligrams are in the vial? | For example, 9.6 mg found against 10 mg on the label |
| Net peptide content | What share of the powder’s weight is peptide? | A percentage; the rest is water and salts left from manufacturing |
| Endotoxin (LAL) | Are there bacterial toxins that can cause fever and inflammation? | A value in endotoxin units (EU) per mg or per vial, against a limit |
| Sterility | Is anything living growing in it? | "No growth" after an incubation period |
Purity is not identity
HPLC separates the contents of a sample and measures each part as it passes a detector. Purity is the main peak’s share of everything detected. That is useful, but it cannot tell you what the main peak is. A vial of the wrong peptide can show 99% purity.
Mass spectrometry answers the identity question by weighing the molecule. The report should show the measured mass next to the expected one. For example, BPC-157 has a molecular weight of about 1419.5, so a result near that value supports the label. A COA with purity and no identity test is only half a report.
Look for both: a purity figure from HPLC and an identity confirmation from mass spec, for the same batch.
Purity, net content and fill are three different numbers
Freeze-dried peptides are never 100% peptide by weight. They carry water and counter-ions (salts such as acetate or TFA) from manufacturing. Net peptide content is the share of the powder that is actually peptide, and it is often well below 100% even when HPLC purity is very high.
Fill or quantity tells you how much peptide is in the vial. That is the number that decides your dose maths. A 99%-pure vial that holds 7 mg instead of 10 mg will under-dose every injection by almost a third.
Endotoxin and sterility
Endotoxins are fragments of bacterial cell walls. They survive filtering and freeze-drying, and when injected they can cause fever, chills and inflammation. The standard test (USP chapter <85>, usually run with a reagent called LAL) reports a value in endotoxin units. A report should state both the result and the limit it was judged against.
Sterility testing checks for living microorganisms by incubating samples, which takes days to weeks. Many research-peptide COAs skip both tests. If they are missing, the COA tells you nothing about whether the product is clean enough to inject.
Red flags
- No batch or lot number, or a batch number that does not match the one on your vial.
- No lab name, address or contact details, or a lab you cannot find anywhere else.
- The same COA used for every batch, or a template with only the product name changed.
- Purity reported with no identity test (no mass spec).
- Dates that do not add up: a test date before the batch was made, or a report years old.
- No chromatogram or spectrum, just a table of round numbers.
- Results that are suspiciously perfect, such as 100.00% purity.
- A COA you can only see after buying, or one the seller will not let you check with the lab.
How to verify a COA
- Match the batch number on the COA to the label on your vial.
- Find the lab independently (not through the seller’s link) and contact it with the report number. Ask whether it issued that report for that sample.
- If the lab offers online verification, use it. Janoshik Analytical, for example, says every report in its database can be checked through the Verify page at janoshik.com/verification or the QR code on the report.
- Look for independent results that the seller did not commission. Finnrick (finnrick.com) publishes community lab results for identity, purity and quantity by vendor. It states its ratings are not endorsements, and neither is this mention.
- If you cannot verify a COA, treat the product as untested.
Why independent testing matters
A seller-supplied COA is a claim made by the party that profits from the sale. It may be genuine, but it was chosen by the seller, often tests a sample the seller picked, and can be reused across batches. Independent tests of vials bought the normal way are the closest thing to an outside check.
Even a good COA only covers what was tested. It does not make an unapproved peptide safe or legal to use. See the regulatory status tracker for where each compound stands with FDA.
Crestigen does not sell peptides and does not endorse any vendor or lab. Talk to a licensed clinician before using any substance.
Common questions
Is 99% HPLC purity good enough?
It is a good sign for purity, but only if a mass spec result confirms the main peak is the right molecule and the fill quantity matches the label. Purity alone does not prove identity or dose.
Why is net peptide content lower than purity?
Purity compares the peptide with other detectable impurities. Net content compares the peptide with the whole powder, which also contains water and salts. Both can be normal at the same time: 99% pure, much less than 100% net content.
Does a COA mean a peptide is safe to inject?
No. Without endotoxin and sterility results it says nothing about contamination, and no COA makes an unapproved compound safe. A licensed clinician can advise on your situation.
Can a COA be faked?
Yes. Template and reused COAs are common. Check the batch number against your vial and confirm the report directly with the lab that issued it.
Try it
- Regulatory Status Tracker: Which peptides are FDA approved, off Category 2 or under review, with dated sources.
- Peptide Dosage Chart: Protocols for 100+ peptides, searchable by name and goal.