How we verify purity

“Purity” is one of the most overused words in this market, so it is worth being precise about what it means and how it is measured. This entry explains the methodology in general terms. For our specific stance and the data on each listing, see how we verify.

What HPLC measures

High-performance liquid chromatography (HPLC) separates the components of a sample as they pass through a column at different rates. A detector records each component as a peak; the area under the main peak relative to the total area gives the purity figure — for example, “≥98% by HPLC.” It is a measure of how much of the sample is the intended compound versus everything else, not a guarantee of biological activity.

Identity is separate from purity

A clean chromatogram tells you the sample is one thing; it does not, on its own, tell you which thing. Identity is confirmed against published reference identifiers — the CAS number, molecular formula, molecular weight, and amino-acid sequence — and, where appropriate, mass spectrometry. That is why we list those identifiers on every product page: they let you confirm you are working with the molecule you intended before you order.

The identifiers we publish

Each product page carries the reference identifiers a researcher needs to confirm a compound: CAS registry number, molecular formula, molecular weight, amino-acid sequence where applicable, and an honestly stated purity figure verified by HPLC. These are standard, checkable identifiers — not marketing language.

What we do not claim

We do not publish per-vial certificates of analysis or per-lot trace documents, and we do not attach a fabricated batch number or a uniform “99.9%” figure to every product. Purity is stated honestly and generally; any HPLC figure shown elsewhere on the site is representative of the method, not presented as a specific vial’s lot result. Overstating this kind of data would be both dishonest and, for research-use-only material, non-compliant.

Confirm it yourself

Because the identifiers are public, you do not have to take our word for the chemistry: the CAS number, formula, MW, and sequence on a listing can be cross-checked against any chemical reference. Read how we verify for the full methods and trust stance.