Lot Number

A lot number, also called a batch number, is the code given to a single production run of a peptide. All analytical statements are tied to it. Purity, identity, appearance and water content belong to a batch, not to a product name, so a certificate whose lot number does not match refers to material that is not in your hands.

Checking and recording the lot

Take the lot from the vial label and make sure the identical code appears on the certificate of analysis that came with the order and on any independent lab report. Log the lot together with your experimental records. When results change unexpectedly from one preparation to the next, check the lot first — a different batch brings a different impurity profile and may bring a different counter-ion ratio and net peptide content.

Traceability and reproducibility

Tracking lots is what separates traceable research from anecdote. It is also the basis of recalls and complaint handling: without a lot, a supplier cannot identify which vials share a defect, and an out-of-specification finding cannot be linked to a specific manufacturing event. Reproducibility in the published literature relies on exactly the same discipline.

Related terms

purity · HPLC. See how to read a peptide COA and the vendor checklist.