Semax Testing & Verification
Mail in your Semax sample for independent RP-HPLC-UV analysis. KMD Analytical reports identity, chromatographic purity, and net-peptide content per vial, measured against a certified reference standard.
What Semax is
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro — the ACTH fragment 4-7 (Met-Glu-His-Phe) with a C-terminal Pro-Gly-Pro extension attached to slow enzymatic breakdown of the parent fragment. It is a linear, unmodified peptide, typically supplied as a lyophilized acetate salt. Two chemical details drive how it is analyzed: the N-terminal methionine is an oxidation-prone residue, and the histidine and phenylalanine give the molecule at least some ultraviolet character, unlike the fully aliphatic short peptides it is often sold beside. Semax is sold on the research-chemical market, frequently alongside or blended with Selank, and is not a regulated drug product in most jurisdictions — so the identity and content of any given vial are unverified until someone measures them.
Why get your Semax independently tested
- Methionine oxidation is the signature degradant: the N-terminal methionine oxidizes readily to methionine sulfoxide during storage, shipping, or reconstitution. The sulfoxide is more polar than the parent peptide and elutes slightly earlier, typically as a front shoulder on the main peak rather than a cleanly separated impurity. On a gradient that does not resolve it, that shoulder is integrated into the main peak and the reported purity is inflated. Chromatographic purity is only meaningful for Semax if the method actually separates the oxidized form, which is why we run a gradient chosen for that separation.
- Variant and substitute confusion: several distinct molecules circulate under the word 'Semax' — plain Semax, N-acetylated and C-amidated variants, and cheaper unrelated short peptides in identical vials. These are different compounds with different retention behavior. A retention-time and UV-spectral match to a certified Semax reference standard establishes whether you have the plain heptapeptide or something else wearing the same label.
- Blend cross-labeling: Semax is routinely co-packaged or blended with Selank, and the two are white lyophilized powders that look identical. Blends sold as a single compound, and swapped labels between the pair, are common. Chromatographic separation resolves each component so it can be examined on its own rather than trusting the stated composition.
- Label mass is not peptide mass: a vial labeled 5 mg or 10 mg contains counterion salt (acetate or TFA) bound to the glutamate and histidine residues, residual moisture from a hygroscopic lyophilizate, and any bulking agent, on top of underfill risk. The net-peptide assay reports milligrams of peptide per vial so you can compare measured content against the printed number.
What we measure on Semax
Every Semax certificate reports exactly three results from reversed-phase HPLC with UV/diode-array detection, quantified at 214 nm. Identity is established by matching retention time and UV spectrum to a certified Semax reference standard; the phenylalanine residue contributes weak absorbance near 257 nm and histidine absorbs in the low ultraviolet, which gives the spectral comparison somewhat more to work with than a fully aliphatic peptide, though it is far weaker than a tryptophan- or tyrosine-containing sequence. Chromatographic purity is reported as area percent of the main peak against total integrated peak area, on a gradient selected to resolve the methionine-sulfoxide form from the parent peak. Net-peptide assay reports milligrams of peptide per vial.
Every result is issued as a certificate of analysis you — or anyone you forward it to — can verify cryptographically. Reporting identity, purity, and milligram content is the point: a vial can be pure and still underfilled, so we report all three. More on purity vs. net-peptide content and how to read a peptide COA.
Our scope — stated plainly
Testing is RP-HPLC-UV against a certified reference standard. This does not include mass spectrometry, sterility, endotoxin, heavy-metal, or residual-solvent testing. Because Semax is a less-common compound, a certified reference standard may need to be sourced before analysis, which can add lead time; where you are submitting a Semax/Selank blend, standards for both components may be required. KMD Analytical is an independent laboratory and does not sell peptides.
KMD is an independent RP-HPLC-UV lab. We do not run LC-MS / mass-spec, sterility, endotoxin, or heavy-metal testing. If your job needs a capability we don't have, we'll say so.
Semax testing — FAQ
Will you catch oxidized Semax, or does it just get counted as pure?
Catching it is the point of the method. Methionine sulfoxide is more polar than intact Semax and elutes just ahead of it, so on a poorly chosen gradient it merges into the main peak as an unresolved shoulder and the purity figure comes out higher than reality. We run a gradient selected to separate that peak, and the oxidized form is then integrated as a related substance rather than counted as product. If the two are not baseline-resolved in a given sample, we say so rather than reporting a number that reads better than the chromatogram supports.
Can you confirm my vial is plain Semax and not an acetylated or amidated variant?
We can tell you whether your sample matches a certified plain-Semax reference standard by retention time and UV spectrum. Terminal modifications change reversed-phase retention, so a modified variant typically fails to co-elute with the standard and is flagged on identity. What RP-HPLC-UV cannot do is tell you which variant you have instead — assigning the structure of a non-matching peak requires mass spectrometry, which we do not offer.
Can you test a Semax/Selank blend and report each one?
Yes, where the two peptides resolve chromatographically. Each resolved component is reported separately, with a net-peptide figure per component where a certified reference standard is available for each. Standards for both may need to be sourced before the run, which we confirm with you first.
Other peptides we test
Retatrutide · Cagrilintide · Tesamorelin · BPC-157 · see the full panel.