How to read a certificate of analysis
A certificate of analysis (COA) is the analytical record for one specific production lot. It is the difference between a purity claim and verified purity. Here is what each section means and how to judge it.
Product name and sequence
Identifies the exact compound tested. The amino acid sequence (or molecular formula) should match the product you are buying — not a similar-sounding analog.
Lot / batch number
The single most important traceability field. A COA is only valid for the lot printed on it. If a vendor shows one COA for every batch they have ever sold, that is a red flag.
HPLC purity
Reverse-phase HPLC separates the sample; the target peak is reported as a percentage of total peak area. Research-grade material is commonly ≥98%. Look at the chromatogram itself, not just the number — a clean baseline with one dominant peak is what you want.
Mass spectrometry
Confirms identity. The observed molecular mass should closely match the theoretical mass for the stated sequence. Purity without identity confirmation tells you the vial is clean, but not what is in it.
Appearance and net quantity
Usually 'white to off-white lyophilized powder' plus the labeled mass per vial (e.g. 10 mg). Discoloration or clumping on arrival is worth flagging.
Test date and testing laboratory
An independent third-party lab name and a recent test date. In-house-only results are weaker evidence than an outside laboratory's report.
Storage conditions
Recommended storage for the lyophilized powder and, where relevant, after reconstitution. This drives how you handle material once it arrives.
Red flags
- No lot number, or the lot number does not match the vial label.
- A purity percentage with no chromatogram or mass spectrum attached.
- Test dates years older than the material being sold.
- COAs available only "on request" rather than published openly.
- No named testing laboratory anywhere on the document.
See ours
Every Veridian lot ships with a published third-party COA you can read before you order — no request form, no gate.
View certificates