Selank: what it is, how it is supplied, and how to choose a research supplier

Selank is a synthetic peptide of seven amino acids: threonine, lysine, proline, arginine, proline, glycine, proline — written Thr-Lys-Pro-Arg-Pro-Gly-Pro or TKPRPGP. The first four residues are the natural tetrapeptide tuftsin (TKPR); the last three, Pro-Gly-Pro, were added to make the chain more stable. Its molecular weight is about 751 Da.

It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences, in the same laboratory that designed Semax, and the two are often listed side by side because they share the Pro-Gly-Pro tail and a similar size.

On a bench it is unremarkable to look at: a white to off-white lyophilized powder with no color of its own, which is one reason the certificate of analysis matters more for Selank than for a colored complex like GHK-Cu. Only the mass spectrum tells you what is in the vial.

In the catalog, Selank is sold as a research reagent: a sealed vial of lyophilized powder with a batch number and a certificate of analysis. Research use only. Not for human or veterinary use.

Because they come from the same laboratory and ship in the same sizes, Selank and Semax are frequently confused in listings. They are different molecules.

A supplier that lists both should show a separate COA for each, with a mass spectrum that matches the right molecular weight. One certificate covering "Selank/Semax" covers neither.

Research Selank comes as a lyophilized (freeze-dried) powder in a glass vial closed with a rubber septum and an aluminum crimp cap. The label states the compound, the net quantity in milligrams, the lot number and the words "research use only".

The catalog offers two sizes — 5 mg and 10 mg — and the price per milligram is lower on the 10 mg vial. The live table at the top of this page is read directly from the catalog, so the prices shown there are the prices in force today. See Selank in the catalog for availability.

What "5 mg" means on the label

The number is the net mass of Selank powder in the vial, as filled, and it is the quantity the certificate of analysis refers to. Five milligrams is a very small amount of solid — often no more than a thin white film at the bottom or on the wall of the glass. An almost empty-looking vial is the normal appearance of a 5 mg fill, not a short fill.

Acetate or trifluoroacetate

Synthetic peptides are usually supplied as a salt. Most research Selank is the acetate; some manufacturers leave the peptide as the trifluoroacetate (TFA) salt from purification. The COA should state which, and a good supplier specifies the counter-ion on the product page. Neither changes the sequence, but the residual TFA content is a purity question.

For a white, odorless powder with no distinguishing feature, the COA is the only thing that separates Selank from any other 5 mg of peptide. A usable certificate carries:

• The laboratory's name and a verifiable identifier. Independent labs (Janoshik is the reference for this market) give each test a number that anyone can look up on the lab's site.
• The lot number — the same lot number that is printed on the vial you receive.
• HPLC purity as a measured percentage, with the chromatogram. "≥ 98 %" printed without a chromatogram is a claim, not a measurement.
• Mass confirmation by mass spectrometry: an observed mass of about 751 Da for the free peptide. A mass around 813 Da would mean the vial holds Semax.
• The date of the test. A certificate older than a few months describes a lot that has probably sold through.
• A photograph of the tested vial wearing the supplier's own label. A manufacturer's certificate showing a bare vial says nothing about what this supplier bottled.

The full checklist, with examples of what a doctored certificate looks like, is in how to read a peptide COA.

Selank is stable as a lyophilized powder when it is kept cold, dark and dry. The catalog's storage line for the sealed vial:

• Temperature: −20 °C for long-term storage; a refrigerator (2–8 °C) is acceptable for short periods.
• Light: keep the vial in its box or in an opaque container.
• Moisture: keep the vial sealed. Let a cold vial reach room temperature before removing it from its bag, so no condensation forms on the glass.
• Shelf life: 24 months from the fill date for a sealed vial stored as above.

Shipping at ambient temperature for a few days does not degrade the sealed powder; that is why research peptides ship without cold packs. The general rules, size by size, are in lyophilized peptides: storage and shelf life.

"Selank" returns a mix of clinics, marketplaces and research suppliers, and "selank for sale" adds resellers with no testing of their own. To sort them, ask six questions of the product page — not of the marketing.

1. Is there a batch COA from a named independent lab, and can it be verified on the lab's site? No verifiable COA = no purchase.
2. Does the COA show the supplier's own label? A manufacturer's certificate, re-used by a reseller, does not cover what was re-bottled or re-labeled.
3. Does the mass spectrum match Selank (about 751 Da), not Semax? The two are shipped side by side and swapped labels happen.
4. Does the supplier ship domestically, from US stock, in a few days? Long international transit is where vials get lost, heated or seized.
5. Does the page describe the product only — composition, purity, storage — with "research use only" stated plainly? A supplier that publishes usage content is a supplier that is easy to shut down; that risk transfers to any order in transit.
6. Is the price at or above the market, not far below it? Third-party testing costs several hundred dollars per lot. A price far under the market is a price that did not pay for testing.

The wider checklist — payment, packaging, what to do if a parcel is stopped — is in where to buy research peptides in the US.

The price of research Selank depends on the size of the vial, whether a third-party test was paid for the lot, and where it ships from. The catalog table at the top of this page shows the current price per vial and per milligram for each size; the 10 mg vial has the lower cost per milligram.

What the price includes at OXpeptides: a sealed, labeled vial from a tested lot, the batch COA, tracked domestic shipping, and a replacement if a parcel arrives damaged. What it never includes: anything other than the reagent itself.

See Selank in the catalog →