What a certificate of analysis does not tell you

Briefly, because how to read a certificate of analysis covers it in full: the compound, the lot number, the assay date, the analytical method, and the measured purity — with identity confirmed by mass spectrometry and purity measured by HPLC, both by a third-party laboratory. It also states storage conditions and lot stability data. Everything below is what is outside that.

A certificate reflects the properties of that lot at the time of testing. From the assay date onward, the material has a history the laboratory did not observe: transit, receipt, storage, every retrieval. If the storage conditions on the certificate have been followed, the certificate remains a reasonable description. If they have not, it may not — and the certificate cannot tell you which. Only the laboratory's own records can. See storing lyophilized reference materials.

HPLC purity is an area percent of detector-visible components; water, residual solvent and non-absorbing salts are outside it. Mass spectrometry confirms molecular mass; it does not, on its own, quantify anything. A certificate reports what its named methods measure and nothing else. Reading the method next to each number is what keeps the number in its proper scope — what HPLC purity actually measures goes into the detail.

Nothing on a certificate — and nothing anywhere on this site — describes a preparation, a dilution, a dose or a use. That is not an omission; it is the position. All material is supplied for in-vitro laboratory research only, we do not publish preparation, dilution or usage instructions of any kind, and we cannot advise on them. Any scientific reference presented anywhere is educational only and is not a product claim. See the disclaimer and research use only.

A certificate is about one lot. Two vials of the same compound from two lots have two certificates, and they may show different figures. Nothing is blended between lots after testing, so the number on the vial always maps to a single assay — and only that assay. A certificate for a lot you do not hold tells you about a supplier's standard, not about your vial. See lot numbers and lot discipline.

A certificate is the supplier's evidence. The strongest evidence a laboratory can hold is its own. Some research groups re-test incoming reference materials as a matter of routine, and a certificate makes that easy to interpret: the method and the result are stated, so a laboratory running the same kind of analysis knows what to compare against and what range of method-to-method variation is normal. The returns policy is built around this: commission independent testing, and if it shows a lot below its stated purity, send the report for a replacement or a full refund. The certificate is not a reason to skip the check; it is what makes the check meaningful. Questions about how to read a specific certificate go to support with the lot number.

The questions a certificate leaves open are answered by the laboratory: its storage records, its handling records, its own procedures, and — if it chooses — its own independent testing. If that testing shows a lot falls below its stated purity, send us the report and we will replace the material or refund it in full under the returns policy. The certificate is where the supplier's answer ends and the laboratory's begins.