A certificate of analysis (COA) belongs to one lot. For a peptide it usually reports identity (by mass spectrometry) and chromatographic purity (by HPLC), and may add net peptide content, water content, counter-ion content or endotoxin.
The lot number on the certificate should match the lot number on the container. A certificate for a different lot, or one without a lot number, says nothing about the material in hand. The register of the shop's certificates is on the certificates of analysis page.
See also
For in vitro laboratory research only. Not for human or veterinary use. This library describes chemistry, analytical methods and published laboratory research; it gives no guidance on use in people or animals.