How to read a COA

A certificate of analysis is only as good as your ability to check it. Work through these questions on any report, from any seller, including us.

1. Who issued it?

   Look for a named laboratory with an address of its own. A certificate issued by the seller’s own “laboratory” or “quality department” is a self-declaration, not an independent test.

2. Can you check it at the source?

   Many independent laboratories let you look the report up on their own website, with a reference or key printed on the report. A “verify” link that leads back to the seller's own domain doesn't count.

3. Does it match your vial?

   The batch ID, the product and the amount on the report should match the label on the vial in your hand. A report for a different batch tells you nothing about yours.

4. Do the dates make sense?

   The report date should come after the batch was made and the sample was received. Some tests take days or weeks, so a report dated the same day the batch was made deserves a closer look.

5. Is the chromatogram unique?

   Every HPLC run produces its own trace, down to the small wobbles in the baseline. If two different batches show identical traces, ask the seller or the laboratory to explain.

6. Does the mass fit the molecule?

   The identity result should sit close to the peptide's theoretical mass, and any molecular formula shown should add up to that mass. A formula that doesn't match its own stated mass is an error worth raising with the laboratory.

7. Are the results too perfect?

   Real measurements vary a little from batch to batch. Identical figures across many batches, or a purity reported as exactly 100.0%, are worth questioning.

Ready to check one of ours? Look up the batch on your vial.