How to Read a Certificate of Analysis
A Certificate of Analysis is a laboratory report covering one production lot. It is issued by the laboratory that ran the tests, not by the seller, and that independence is the entire reason it is worth reading. This page explains what the document reports, how to tie it to the vial in your hand, and, just as importantly, what it does not tell you.
Who issued it
Start at the top of the certificate, not the middle. A certificate is only as good as the laboratory behind it, so the first things to look for are the laboratory’s name, its location, the date the analysis was run, and the lot the report covers. A document with no issuing laboratory named on it is not a certificate of analysis. It is a claim in a serif font.
Identity: is this the right molecule?
Identity is normally established by mass spectrometry. The instrument measures the mass of the material in the sample, and that figure is compared against the calculated mass of the intended peptide. Agreement within the instrument’s tolerance is what confirms identity.
This matters more than it sounds. Several compounds sold as research peptides are fragments of larger proteins, and the fragment and the parent protein are different molecules with different published records. Identity testing is what tells you which one arrived.
Purity: how much of the material is the target?
Purity is typically measured by high-performance liquid chromatography. The sample is separated into its components and the target peak is reported as a percentage of everything the detector saw.
Read that percentage as belonging to the lot on the certificate and to nothing else. Purity is measured once, on one batch, by one laboratory. It is not a property of a product line, it does not carry across to the next production run, and any figure quoted outside the context of a specific lot is decoration.
Quantity: does the vial size match the label?
Quantity verification confirms how much peptide the vial contains. That is what the milligram figure on the label means: a quantity of material. It is not a strength, a potency, or a dose, and it should never be read as one.
Tying the certificate to your vial
Every certificate names the lot it covers. Match that lot number against the one printed on your vial label. If the two do not match, the certificate describes a different batch of material and tells you nothing reliable about yours. If you cannot locate a certificate for a lot you have received, ask us and we will send it.
What a certificate does not tell you
- Whether the compound is safe. A certificate reports composition, not toxicology.
- What the compound does. That question belongs to the research literature, and for most of these molecules that literature is preclinical.
- Anything about a different batch, including the next one.
- Whether the material was handled correctly after it left the laboratory. Storage and handling are yours to control.
- Sterility or endotoxin content, unless the certificate explicitly reports those tests. Most do not.
If something looks wrong
A missing laboratory name, a lot number that does not match your vial, an analysis date that predates the production date, or a report with no chromatogram attached are all reasons to ask a question before using the material. We would rather answer that question than have you assume.