You shouldn't have to take purity on faith.

Purity by reverse-phase HPLC

Purity is quantified by reverse-phase high-performance liquid chromatography. The sample is separated on a C18 column under a water/acetonitrile gradient with trifluoroacetic acid as the ion-pairing agent, and detected by UV absorbance in the 214–220 nm range, where the peptide bond itself absorbs.

The reported figure is area percent: the area of the main peak as a proportion of total integrated peak area. That is the number the industry quotes, and it is worth being precise about what it means — it describes the proportion of UV-absorbing material eluting as the target peak. It is not a mass assay, and it does not by itself establish net peptide content, which is why the certificate reports the two separately.

Acceptance specification: ≥ 98.0% by RP-HPLC. Results are reported to one decimal place, with the specification printed beside them, so you see the margin rather than a pass mark.

Identity by LC-MS

Purity says how much of the material is one thing. It does not say what that thing is. Identity is confirmed by liquid chromatography–mass spectrometry: the observed monoisotopic mass is compared against the theoretical mass calculated from the sequence, and the lot conforms only when they agree within instrument tolerance.

This is the assay that catches the failure mode that matters most in this category — a highly pure sample of the wrong peptide. A COA reporting purity without identity is telling you half the story.

Endotoxin by LAL

Bacterial endotoxin is measured by the Limulus amebocyte lysate assay and reported in endotoxin units per milligram. Endotoxin is a lipopolysaccharide from the outer membrane of Gram-negative bacteria; it survives conditions that kill the organism that produced it, so sterility does not imply low endotoxin.

It matters here because it confounds cell-based work directly rather than subtly. Endotoxin is a potent agonist of TLR4 signalling, and at concentrations well below anything visible it will activate macrophages and other immune-competent cells, driving cytokine release and inflammatory readouts that look exactly like a treatment effect. If you run primary cells, immune assays, or anything downstream of NF-κB, an unscreened reagent is a live source of false positives.

Who performs the testing

Purity and identity testing is performed by an independent laboratory, independently of our production, so the figure on the certificate is not self-reported. Testing a lot in the same facility that made it removes the only real check in the chain, which is why the assay work is contracted out.

How certificates are archived and retrieved

Every certificate is filed against its lot number, and the lot number is printed on the label of the bottle it describes. A COA therefore always resolves to one specific production run — not to a representative batch, and not to the product line in general.

• The certificate for the lot you were sent ships with the order.
• Signed-in customers can download the certificate for any past order from their account.
• If you have the lot number from a label, send it to us and we will return the PDF — including for lots that are no longer in stock.

What this material is not

Everything on this site is supplied as a reference material for in-vitro laboratory research. It is not a drug, not a supplement, and not for human or veterinary use. The testing described above establishes what is in the bottle to a research standard; it is not a pharmaceutical release process and it makes no statement whatsoever about safety in a living subject.