Research peptide COA guide: how to read a certificate of analysis
What a COA proves, what it cannot, and how to check one in a minute.
The short version
A certificate of analysis, or COA, is a lab report on one specific batch of a compound. A useful one names the compound, ties itself to a lot number and test date, states the test method, and reports a purity figure. It can show that a given batch is what it claims and how pure it is. It cannot tell you the product is safe, that your particular vial matches, or anything about human use. Here is how to read one.
What is on a real COA
- The compound name and, ideally, its structure or molecular formula
- A lot or batch number, and a test date
- The testing method, usually HPLC for purity and mass spectrometry for identity
- A purity result, often as a percentage
- The lab that ran the test, ideally an independent one
The method matters more than the number
HPLC separates a sample so the purity percentage reflects how much of it is the target compound. Mass spectrometry confirms identity by weighing the molecule. A purity figure with no method, or a certificate that is just a logo and a big number, is not proof. A real report shows the chromatogram or spectrum, or at least names the method and lab.
What a COA cannot tell you
A COA covers the batch that was tested, not necessarily the vial in your hand, so lot matching is what connects the two. It says nothing about safety, sterility for injection, or fitness for human use, and none of these compounds are for human consumption. Treat a COA as one piece of evidence about identity and purity, not a green light.
COA red flags
- No lot number, or a lot that does not match the product
- No test date, or a date years old
- No method named, or purity stated with nothing behind it
- An image that looks copied or edited, or a report that will not open
- Only an in-house report, with no independent testing available
Put it to use
Before you trust a source, ask for the batch COA and run the checks above. Then use our supplier evaluation checklist for the wider picture, and the calculator once you have a vial in hand.