What a lot number on a vial does and doesn't prove
Updated 2026-10-07 · Laboratory documentation · Research use only
A lot number names one production run of a material. On this site it is also the link between a vial and a certificate of analysis: each certificate in our library prints the lot it reports on, and the lot number on a vial is meant to say which run that vial came from. The link is useful, and it has limits. This page sets out both, in laboratory terms only.
What a certificate describes
A certificate of analysis is a laboratory's report on a sample. For the certificates in our library, AxisPharm, LLC tested a sample from one lot and printed the results under that lot number with a report date: identity by LC-MS, UV purity and, for most lots, endotoxin by LAL assay. The figures describe that sample as the laboratory measured it. On some of the PDFs, the files' own data show that the printed lot number was changed after the report date, before the PDFs reached us.
What the lot number links
A lot is meant to be one uniform batch: made in one run, under one set of conditions, then divided into vials. That is why a test on one sample is reported for the whole lot, and why the lot number is the link between a vial and the report. A certificate that prints the same lot number as a vial is the laboratory's report on a sample from that lot. A certificate with a different lot number reports on a different run, however close the product name and size.
The same product can be made in more than one lot, and each lot gets its own certificate. That is why some sizes in our library list more than one lot, and why figures such as purity can differ between them.
What it doesn't prove
- That a particular vial was tested. The laboratory tested a sample drawn from the lot, not each vial in it. The lot number ties a vial to the report on that sample; it doesn't make the report a test of that vial.
- That every vial in the lot matches the sample. Reporting one sample for a whole lot relies on the lot being uniform. A single certificate doesn't measure variation from vial to vial.
- Anything that happened after the test. The certificate doesn't cover how a vial has been stored, shipped or handled since, and storage affects how material changes over time (see peptide storage).
- What the certificate doesn't report. Ours don't report net peptide content, water, counterion or residual solvents; reading a certificate of analysis covers what that leaves open.
- That the document itself is sound. A lot number connects a vial to a document. It says nothing about whether that document is complete, or whether the file was changed after it was issued (see below).
How to look a lot up
The lot lookup on our lab testing page takes a lot number and opens the certificate published for it: the product and size, the report date, the laboratory and the PDF. Enter the lot as printed, letters and numbers together; capitals don't matter. For example, NAD1000VAS0826 opens the certificate for NAD+ 1000 mg, reported August 24, 2026. If nothing comes up, no certificate is published under that lot number; contact us with it and we can say where that lot is in testing.
For some lots, the certificate library also links to AxisPharm's own copy of the certificate on its website, with the date we last downloaded it and compared the two files.
Where the certificates come from
PepsMartUSA doesn't order these tests. AxisPharm, LLC issued each certificate in the library, our supplier, Protixa, provided them to us, and we publish each PDF as provided (more in where the certificates come from). The files' own data show that some of those PDFs were changed after their report dates, before they reached us. A lot number can't show whether a file was changed. Where the laboratory hosts its own copy, comparing the two files can.
Questions about lot numbers
Does a matching lot number mean the vial itself was tested?
No. The laboratory tested a sample from the lot. A matching lot number ties the vial to the report on that sample; it doesn't mean that vial went through the tests.
Why can two lots of the same product show different results?
Each lot is a separate production run with its own certificate, so purity and the other measured figures can differ from one lot to the next. A certificate for one lot says nothing about another.
What if a lot number isn't in the lot lookup?
Then no certificate is published under that lot number. Check that it was entered as printed, then contact us with it and we can say where that lot is in testing.
Does a certificate cover storage after the test?
No. It reports results as the laboratory measured them. How a vial was stored and handled afterwards isn't covered; storage conditions for sealed vials are under peptide storage.
Can a PDF here be compared with the laboratory's own copy?
For some lots. Those entries in the certificate library link to AxisPharm's own copy as “Lab-hosted copy”, with the date we last compared the two files.