Guide
How to Read a COA
A certificate of analysis tells you what is actually in the vial. Reading one takes two minutes once you know the parts. Here is the anatomy, top to bottom.
The header: who tested it
The report should name the laboratory and carry a report or task number. No lab name means no accountability. The task number is what lets you verify the document later.
Sample identity and lot number
The report describes the sample submitted and the batch it came from. The lot number on the report should match the lot number printed on your vial. A COA for a different lot tells you nothing about yours.
Purity
Purity is usually measured by HPLC and stated as a percentage. It tells you how much of the material is the target compound versus related impurities. For research peptides, credible reports typically show 98% and above. Be suspicious of a product page that states a different purity than its own linked report.
Identity and mass
Mass spectrometry confirms the compound is what the label says. The measured mass should match the theoretical mass of the peptide within a small tolerance. Purity without identity is half an answer.
Quantity and extras
Better reports also state measured content per vial — whether a 10mg label actually contains 10mg. Some vendors add endotoxin or sterility testing on separate reports.
Verify the report is genuine
A PDF can be edited. The check that matters: take the task number to the lab's own verification portal and confirm the values match. Reports that resolve on the lab's portal are trustworthy; reports that exist only on the vendor's server are just claims.
Worked example: Curo publishes a report for every lot, and each one links to Janoshik's verification portal. Open one and follow the verification link to see the full loop.