September 21, 2026
How to read a certificate of analysis
Purity, identity and batch numbers — what each line on a COA actually tells you.
A certificate of analysis (COA) is the document that proves a compound is what it claims to be.
What to look for
- Batch / lot number — should match the label on your vial.
- Purity (HPLC) — shown as a percentage; research grade is typically 98% or higher.
- Identity (mass spec) — the measured molecular weight should match the expected weight.
- Test date and lab — ideally an independent, third-party laboratory.
Red flags
Missing batch numbers, no named lab, or purity results with no chromatogram are all reasons for caution.
For in-vitro research use only.