What is a COA and what should I actually look at in it?
Updated: 2026-09-09 · Buying, quality and COA
Short answer
A COA is a lab report with the results of tests run on a sample represented as coming from a batch. Reading one well reduces risk, but it does not validate the product: a matching lot number improves traceability, it does not prove chain of custody, and a PDF may not be authentic. This is document literacy, not a guarantee that an unapproved product is safe.
In plain English
- Batch number: must match your vial label.
- Analysis date: a years-old COA says little about the current batch.
- Method: HPLC can support purity assessment and mass spectrometry can support identity, depending on the method and its validation.
- A 'purity %' is not the same as verified content, sterility, endotoxin status, potency or clinical safety.
What we know
- HPLC and mass spectrometry are the usual techniques, but their value depends on the method, its validation and the identity of the sample tested.
- A COA with no batch number or identifiable lab is not verifiable.
What we don't know yet
- A COA says nothing about sterility, endotoxins, or how the product was handled after testing.
Sources
External links to official sources or peer-reviewed studies.