Peptide lot numbers explained: find the lot, look up its COA and keep traceability

US manufacturing rules define a lot number (also called a control or batch number) as any distinctive combination of letters, numbers or symbols from which the complete history of a batch or lot can be determined: its manufacture, processing, packing, holding and distribution (21 CFR 210.3). A lot is a batch, or an identified portion of one, with uniform character and quality within specified limits.

For a research peptide this means the lot number is the link between the physical vial on your bench and the analytical results for that batch. Purity, identity by mass and measured quantity are properties of a tested lot, not of a product name.

The lot is printed on the vial label, usually as a short code of letters and digits such as RT10072726. Lot formats differ between manufacturers and batches, so do not try to decode dates or meanings from the characters; treat the code as an identifier only.

A cap color is not a lot number. 2 of our published reports identify the sample by cap color only, so the lookup never matches them to a vial; we show them on the product pages but do not present them as lot-traceable.

Work through these steps. The lookup matches published reports only and never applies one lot's results to another lot.

1. Find the lot or batch number printed on the vial label. It may be marked "Lot", "Batch" or "LOT#".
2. Copy it exactly, letters and digits. Case, spaces and dashes do not matter to our lookup, but every character does.
3. Enter it on the lot lookup at /verify, or open /verify/ followed by the lot in lowercase (for example /verify/rt10072726).
4. Check that the lot printed on the certificate matches the lot on your vial character for character.
5. Note the issuing laboratory, report date, method, purity and measured quantity in your lab notebook next to the lot number.
6. If the lot is not found, request that lot's certificate on the testing page with the lot number and order number.

A lot that is not found means its report is not published on this site. It does not mean the lot was untested, and it does not mean it was tested. Not every lot has a published report. Ask for the exact certificate on the testing page, and keep the vial's lot number with your order number so the reply can be matched.

Check the obvious first: a misread character (0 and O, 1 and I, 5 and S) is the most common reason a valid lot is not found.

Traceability only works if the lot is written down when the vial arrives. Record the compound, lot number, vial quantity, receipt date, storage location and the COA's report number and laboratory together, and keep a copy of the certificate with the record.

When results look unexpected, the lot record lets you check whether two experiments used the same batch and whether the certificate for that batch covers the property in question. Once a vial is in use, treat the lot record as part of the experiment's metadata.

Treat a certificate as unverified for your vial if any of these apply:

1. The lot on the certificate differs from the vial label by even one character.
2. The certificate has no lot at all, or only a product name.
3. The same certificate is offered for several different lots.
4. The issuing laboratory cannot find the report on its own lookup or by email.
5. The certificate names no laboratory, or no report or accession number you could check with the lab.