Guide · 1 min read · Updated October 6, 2026
How To Read A Certificate Of Analysis
Four lines on a lab report tell you almost everything. Here is where to look.
A certificate of analysis, or COA, is the lab report for one specific batch. It is the only document that says what is actually in the vial.
1. Match The Lot
Find the lot or batch number on the report. It must match the lot printed on your vial label. A certificate for a different lot tells you nothing about yours.
2. Check Who Tested It
The report should name the laboratory and carry a date. An independent lab is one that is not the seller.
3. Find The Identity Result
Mass spectrometry measures molecular mass. The measured mass should match the expected mass for the compound named on the label.
4. Find The Purity Result
Purity is normally reported from HPLC as a percentage. The number on a product page should be the same number printed on the report.
If Any Of These Are Missing
Ask for them before you order. A seller who has the report can send it in a minute.