Why does a COA need a batch or lot number?

A certificate of analysis reports results for one specific production run, not for a product in general. The batch or lot number is the link between the paper and the physical vial. Without it, you can't tell whether the purity and identity numbers describe the unit in your hand or some other run entirely. In regulated pharma manufacturing, batch-level testing is the baseline. FDA's GMP rules (21 CFR 211.165) require laboratory testing and conformance to specification for each batch before release, and the COA is the document that ties those results to that lot number and its manufacturing records. For independent peptide labs the same logic applies to verification. Janoshik assigns each tested batch a unique reference key; entering it at the lab's verify portal returns the original test data, so you can confirm the COA wasn't altered. Check that the batch or lot on the vial matches the COA exactly. If it doesn't, the report doesn't describe your product. These are research-use-only materials, not approved for human consumption.