What “98% Purity” Actually Means: Our Complete Testing Record

Almost every research-peptide vendor prints a number like >98% purity somewhere on the page. Very few will show you the lab report behind it, and fewer still will show you the report for the exact lot in the vial you receive. That gap between the claim and the evidence is the whole story, so it is worth being precise about what the number is.

A specification is a promise, not a measurement

>98% is a specification. It is the floor a lot has to clear to ship. It is not the result of measuring your vial. Two vendors can both print >98% while one is clearing the bar at 98.1% and the other at 99.6%, and from the claim alone you cannot tell them apart. The only way to know what you actually have is to read the certificate of analysis (COA) for that specific lot and see the measured number.

So we publish it. Below is every lot we have released, with the measured purity from its third-party COA. You can check our numbers before you ever buy anything.

Our numbers, every lot

As of September 11, 2026, across 32 published lots and 38 individual purity measurements (blends carry one measurement per component), the mean measured purity is 99.35%. The lowest single figure is 99.13%, the highest is 99.65%. Not one measurement sits below 99.0%. The table below is the live lot register, so it updates whenever a new lot is published; the figures in this paragraph were calculated from that register on the date stated.

Every lot is looked up one at a time on our public register, and each row links to the full COA. The number on this page is the number on the certificate is the number on the vial in your hands.

Why our written guarantee sits below our real floor

Our published guarantee is 98.0%. Our measured floor across every lot is 99.13%. That gap is on purpose. Purity measured by HPLC carries normal lab-to-lab analytical variance: run the same material at two labs and you can see a few tenths of a percent of difference from the method alone, not from anything being wrong with the material. Setting the written guarantee a full point below our real results means the promise holds even against that variance. We would rather under-promise on paper and over-deliver on the certificate than the other way around.

How to read the blend numbers

Some lots show more than one number, like the KLOW blend at 99.35% / 99.48% / 99.58% / 99.34%. A blend is more than one peptide in the same vial, so its COA reports each component separately, and the honest way to publish it is to show every component rather than an average. It is also why the single lowest figure in our whole library, 99.13%, sits inside a two-component blend lot: it is one component of one blend, reported plainly rather than smoothed away.

What the number does, and does not, tell you

Chromatographic purity answers one question: of what is in the vial, how much is the target peptide versus related impurities. It is measured, on this catalog, by HPLC and reported against the lot. Identity, a separate question, is confirmed by its own analysis on the COA. Net peptide content, the share of the powder that is peptide rather than counterions and water, comes from amino acid analysis, not from the chromatography purity figure. Reading all three parts of a COA together is what tells you what you actually have, which is why we also keep a plain-language guide to reading a COA. For a worked example on a large peptide, see our guide to reading a Tesamorelin COA.

Check us, do not take our word for it

Enter any lot number from your vial on our register to pull its COA. If you have not bought anything yet, the register is the whole library, open to read first. That is the point: you should be able to verify the claim before you trust it. Learn more with How to Read a COA and What Research Use Only Means.

All products are sold strictly for laboratory and research use only, and are not for human or animal consumption.