Short answer: every production batch is made separately and can differ in purity, content or contamination. A COA is only evidence for the batch it tested, so the useful question is not “is this product tested?” but “is this lot tested?”.
Batches vary
Peptide synthesis, purification, lyophilization and filling are done batch by batch. Small changes in any step can change the impurity profile or the amount per vial.
Generic vs. batch-specific COAs
- Generic COA: one report used for every sale, sometimes for years. It shows that one sample passed, not that current stock did.
- Batch-specific COA: a report whose lot number matches the lot printed on the vial you receive.
What to look for
- A lot number on the vial label.
- The same lot number printed in the COA itself.
- A recent report date for the current lot.
- A new COA when the lot changes.
Why sample source matters
Lab reports often state that results apply only to the sample received, and whether the lab or the client collected it. A COA is strongest when the tested sample clearly comes from the same lot being sold.
How Guardian Labs publishes batch results
Guardian Labs publishes each available COA as an HTML testing record with its lot number, laboratory, report date and results, linked to the product and to the original PDF. See all records on the Certificates of Analysis page.
Related guides
- What Should a Peptide COA Contain?
- How to Read a Peptide COA
- Identity Testing vs. Purity Testing
- How to Verify Third-Party Lab Testing
← All Research & Education guides · Certificates of Analysis
All Guardian Labs products are sold for laboratory research use only. They are not for human or veterinary use, and nothing on this page is medical advice.