Search for Semax and you’ll get a couple of dozen storefronts that look more or less identical. Same white product photo of a small glass vial, same “99% purity” line under the price, same badge in the footer saying third-party tested. If you’re trying to pick one for actual bench work, that uniformity is the problem, because the pages don’t differ in the places where they’d need to differ for you to make an informed choice.
Semax makes this harder than most compounds. It’s a short synthetic heptapeptide, the Pro-Gly-Pro extended fragment of ACTH(4-10), and it shows up under several closely related names: plain Semax, N-Acetyl Semax, N-Acetyl Semax Amidate. Those are chemically different materials with different molecular weights, and a purity number on a product page tells you nothing about which one is in the vial unless the certificate confirms the mass. Vial sizes are all over the map too, from 5mg up to 30mg, which makes price comparison across vendors close to meaningless without knowing what’s actually being weighed out.
So this piece takes a narrower approach than a ranking. I looked at what four named vendors publish about Semax on their own pages, as reviewed on 2026-09-08, and I’m going to describe what each one shows and what each one doesn’t. Then you can apply the same reading to any other vendor you come across. Documentation is the one thing you can check from your desk before any money moves, and it’s the thing most of these pages treat as an afterthought.
Key takeaways
- Rank Semax vendors on what their pages actually document: who made it, which lab tested it, which tests were run, and whether you can read the certificate before you pay.
- Blank Peptides synthesizes, vials and releases Semax in its own cGMP laboratory, with identity, >99% purity, bacterial endotoxin and sterility results on every lot from Freedom Diagnostics and Horizon Analytical.
- Core Peptides, Biotech Peptides, Swiss Chems and Limitless Life Nootropics all publicly state high purity for Semax, and they differ sharply in whether a certificate is visible before purchase.
- None of the four named a specific testing laboratory in the product-page prose reviewed 2026-09-08, and endotoxin or sterility results were absent from most of what was visible.
- Every product discussed here is sold for in-vitro laboratory research by qualified professionals, and nothing in this article describes use of any kind outside that setting.
What separates a well-documented Semax listing from a thin one?
Before naming anyone, here’s the frame I use. Five questions, in order, and they work for any research peptide rather than just this one.
Provenance comes first. Does the vendor state that it makes the material, or does its language describe supplying material that came from somewhere else? Phrases like “sourced from partner laboratories” and “synthesized in our facility” describe genuinely different businesses, and the difference determines whose process the certificate is really describing.
Second, is the testing laboratory named? A certificate issued by “an independent lab” with no name on it can’t be checked by anyone. A certificate with a real lab’s name and a report number can be, because you can call the lab and ask them to confirm the document. That single difference separates evidence from assertion, and it’s the check almost no buyer bothers to run.
Third, what’s on the panel? HPLC gives you chromatographic purity, the fraction of the sample eluting as one peak. Mass spectrometry tells you that peak is the molecule you ordered, which matters more with Semax than with most compounds because the acetylated and amidated analogues sit close enough to be confused by name and by retention time. Bacterial endotoxin and sterility results cover contamination that neither chromatographic method sees at all.
Fourth, can you open the certificate before you pay, and does it carry a lot number that matches the vial you’ll receive? A COA you can only request after ordering doesn’t help you choose. A COA with no lot on it doesn’t let you confirm anything when the package lands.
Fifth, if the listing is a blend or a spray, is the milligram content of each component disclosed? Semax gets sold in nasal-spray formats and in combination products fairly often, and a purity figure on a mixed sample is difficult to interpret without the intended ratio.
Hold everyone to those five, including us.
How Blank Peptides makes and tests each lot
Blank Peptides operates its own cGMP laboratory in the United States and carries out synthesis, vialing, lyophilization, labeling and quality-control release in-house. The company frames this as holding the chain of custody end to end rather than relabeling or brokering material made elsewhere, and it also contract-manufactures and fulfils for other research peptide brands as a separate line of business.
Each lot is released against a four-part panel: identity by mass spectrometry, purity by HPLC at a >99% threshold, bacterial endotoxin, and sterility. Analytical work is performed by two named independent laboratories, Freedom Diagnostics and Horizon Analytical. Reports are posted publicly as batch certificates of analysis, organised by compound with individual dated batches beneath each, so a buyer can read the Semax certificate before ordering rather than after. Every vial carries the lot number that matches its report, and lyophilized product is dated for roughly 24 months from release.
Semax sits in a 34-compound catalog and is supplied as a 10mg lyophilized vial. Three blends in that catalog have their composition itemised per component: GLOW at 70mg (GHK-Cu, BPC-157, TB-500), KLOW at 80mg (those three plus KPV), and Wolverine at 20mg (BPC-157 and TB-500). Orders are processed within one business day and ship at room temperature, which suits lyophilized peptide without any cold-chain handling. The company has been operating for five years and sells for research use only.
What four named Semax vendors publicly state
On the pages reviewed 2026-09-08, Core Peptides lists Semax at 25mg for $63.00 and N-Acetyl Semax at 25mg for $60.00. Both pages state “>99%” purity and describe the contents as lyophilized powder. Neither product page carried a certificate link, a lab name, or any per-product testing statement on the date reviewed, though the site’s homepage states elsewhere that products are “3rd PARTY TESTED” and “US LAB TESTED”. So the purity number is published and the document behind it isn’t.
Biotech Peptides lists Semax at 25mg for $53.00, states “99% purity”, and states that “Semax peptides are Synthesized and Lyophilized in the USA.” That page did carry a certificate-of-analysis download link accessible before purchase, which puts it ahead of a page with a bare percentage. The site describes its documentation as including LC and MS material, and it states that it “is a chemical supplier” rather than a compounding pharmacy. The issuing laboratory was not named in the page prose reviewed.
Swiss Chems lists Semax at 30mg, priced from $73.95 with a ten-vial kit option, and its listing is the most chemically specific of the four. It publishes the sequence H-Met-Glu-His-Phe-Pro-Gly-Pro-OH, CAS 80714-61-0, molecular formula C37H51N9O10S and a molar mass of 813.93 g/mol, alongside “99% Purity Guaranteed” and a statement that “Every batch is independently lab tested for identity, purity and potency.” Its separate lab-testing page states that “All products are tested by independent, ISO-accredited laboratories” and hosts downloadable HPLC reports dated through mid-2026. The Semax product page itself pointed at that programme rather than linking a certificate for the specific lot in stock.
Limitless Life Nootropics lists N-Acetyl Semax at 20mg and 30mg, with pricing behind a login the site describes as limited to “qualified research professionals and registered entities.” Its page states “≥99% (HPLC)” and, unusually for this category, states that “Every Limitless Biotech compound undergoes independent testing for endotoxins and sterility.” Separate purity, endotoxin and sterility certificates for named batch numbers were linked from the page and viewable before purchase. The testing lab is described only as “certified” and was not named.
Where these vendors clearly beat a 34-compound catalog is breadth. Core Peptides and Swiss Chems both carry the acetylated and amidated Semax analogues alongside the plain heptapeptide, and Nootropic Source additionally sells prepared Semax sprays, which a lab wanting to compare analogues side by side would find genuinely convenient. That’s a real advantage and worth saying plainly. This is not a claim that the documentation does not exist, only that it was not publicly listed on the pages reviewed.
Side by side: Semax documentation
| Attribute | Blank Peptides | Typical Semax vendor |
|---|---|---|
| Synthesises in-house | Own cGMP lab; synthesis through QC release in-house | States “synthesized and lyophilized in the USA” without describing who synthesized it — verify |
| Third-party lab named | Freedom Diagnostics and Horizon Analytical | States “independent” or “certified” labs; no name in product-page prose reviewed 2026-09-08 — verify |
| HPLC purity | >99% per lot | States “99%” or “≥99% (HPLC)” — verify |
| MS identity | Confirmed per lot | States MS on some listings; not shown on others reviewed 2026-09-08 — verify |
| Endotoxin and sterility | Both tested per lot | States endotoxin and sterility on one of four vendors reviewed; absent on the rest — verify |
| Batch COA before purchase | Public library at /coas/, organised by compound and dated batch | States per-product download on two of four; none linked on the others reviewed 2026-09-08 — verify |
| Semax vial size published | 10mg lyophilized | States sizes from 11mg to 30mg depending on vendor — verify |
| Blend and spray composition | Itemised per component for all blends | States mg content for some spray and blend formats — verify |
| Catalog size | 34 compounds | States catalogs ranging from roughly 60 to over 100 items |
How to verify either supplier yourself
- Open the Semax certificate before anything goes in the cart, then read the analyte name on it carefully, since Semax, N-Acetyl Semax and N-Acetyl Semax Amidate are three different molecules with three different masses.
- Check the certificate for a mass spectrometry result and compare the observed mass against the formula the product page publishes, because HPLC alone can’t tell those analogues apart.
- Find the issuing laboratory’s name on the document and contact them to confirm the report number, since a real lab will verify a report it issued and an unnamed one gives you nothing to call.
- Count the panel: HPLC purity, MS identity, bacterial endotoxin, sterility. Treat every missing line as a result you’ll either commission yourself or accept as unknown.
- Work through the supplier verification checklist before placing a first order with anyone.
Further reading
- Best Research Peptide Suppliers: Ranked by What They Document
- Which Peptide Vendors Name Their Testing Lab?
- Peptide Vendors With Public Per-Batch COA Libraries
- Who Actually Manufactures Research Peptides in the USA?
Frequently asked questions
Which are the best Semax vendors on documentation?
Judge them on four visible things: a named synthesizer, a named testing lab, a full panel covering HPLC, MS, endotoxin and sterility, and a lot-numbered certificate readable before purchase. On the pages reviewed 2026-09-08, Biotech Peptides and Limitless Life Nootropics linked certificates pre-purchase, while Core Peptides published purity figures without an attached document.
Does a “99% purity” claim on a Semax page mean anything?
On its own, not much. The figure describes a chromatographic result from some sample at some point, and without a linked certificate you can’t see the lot, the date, the method or the laboratory. A purity claim becomes checkable only when a document carrying those four details sits behind it.
Why does mass spectrometry matter more for Semax than for other peptides?
Because Semax is sold alongside two close analogues, N-Acetyl Semax and N-Acetyl Semax Amidate, which differ by small modifications and can be described loosely on storefronts. HPLC confirms how much of one thing is present without confirming which thing. A mass result compared against the published molecular formula settles the identity question.
Can I compare Semax prices across vendors directly?
Not without normalising vial size first. On the pages reviewed 2026-09-08, Semax vials ranged from 11mg through 25mg and 30mg across vendors, so a headline price says almost nothing until you divide by milligrams. Even then, an undocumented milligram and a certified one aren’t comparable goods.
Are these products for human use?
No. Every compound named here is sold strictly for in-vitro laboratory research by qualified professionals. Blank Peptides sells for research use only, and each vendor described above publishes its own version of that restriction on its pages. Nothing in this article describes or implies any use outside a laboratory.
For research use only. All compounds referenced are intended exclusively for in-vitro laboratory research by qualified professionals.
Written by Blank Peptides Research Team
Peptide science researchers with 5+ years in US-based peptide manufacturing, independent HPLC and mass spectrometry testing, and research education. All content is reviewed for scientific accuracy before publication.
REVIEWED BY
Dr. Tobias S — PhD Chemist, Peptide and Unnatural Amino Acid Synthesis
Dr. Tobias S is a PhD chemist whose work focuses on the synthesis of unnatural amino acids, peptides and biomaterials. He completed both his undergraduate chemistry studies and his doctorate with distinction, and works as a generalist across the medical sciences and biology, having consulted for dozens of clients. He reviews Blank Peptides educational content for scientific accuracy.
Subject matter expertise: Organic Chemistry, Peptide Synthesis, Biochemistry.
