Quick answer
For Selank, the supplier checks that matter most are a batch-specific HPLC purity result, a mass spectrometry result matching the heptapeptide's mass (about 752 Da), and a lot number on the vial that matches the certificate.
- Sequence: Thr-Lys-Pro-Arg-Pro-Gly-Pro, a tuftsin analog; formula C33H57N11O9
- V8 listing: Selank, 10 mg lyophilized powder, ≥98% HPLC purity
- Check first: method-disclosed HPLC, mass-spec identity, lot traceability, consistent research-use labeling
- Warning sign: a price with no plausible relationship to the cost of synthesis, purification and testing
- Research use: For laboratory research use only; not for human consumption.
What Selank is, and why sourcing it needs care
For laboratory research use only; not for human consumption.
Selank is a synthetic heptapeptide studied primarily in anxiolytic and cognitive research models, with most of its foundational literature originating from Russian pharmacological institutions rather than the Western peptide research base most labs are used to evaluating. That origin doesn't change what a researcher should demand from a supplier; it just means there's less built-in familiarity to lean on, so the documentation matters more, not less. The compound-level background is in the Selank research overview and what is Selank.
Structurally, Selank is the tuftsin tetrapeptide (Thr-Lys-Pro-Arg) extended by a Pro-Gly-Pro tail. Tuftsin is a fragment of immunoglobulin G heavy chain, and the added tripeptide is the modification that was designed to slow enzymatic breakdown of the native fragment. The practical consequence for a buyer is that the molecule is small (average mass about 752 Da) and rich in proline, which affects both how it behaves on a chromatography column and how its mass spectrum looks.
| Property | Value | Why it matters when sourcing |
|---|---|---|
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Defines what MS identity must match |
| Molecular formula | C33H57N11O9 | Listed on the V8 product page |
| Average mass | ≈ 751.9 Da | Expected [M+H]+ near m/z 752.9 |
| Residues | 7 (three prolines, two basic: Lys, Arg) | Short and polar; early HPLC elution; no UV-active aromatic side chain |
| Supplied form (V8) | Lyophilized powder, 10 mg | Handled as a dry, cold-stored reagent |
What to check before ordering
- HPLC purity with the method disclosed. A percentage on a label means little without the analytical method behind it. See HPLC purity analysis.
- Batch-specific Certificate of Analysis, tied to the exact lot shipped, not a template reused across production runs. See how to read a COA.
- Mass spectrometry identity confirmation. Verify that the material's molecular weight matches Selank's sequence, not just that something eluted at a plausible retention time.
- Third-party or independent testing where available, rather than solely in-house claims. See third-party testing explained.
- Lot traceability. The lot number printed on the vial should match the lot number on the COA. If they don't, the documentation isn't linked to what shipped.
- Storage guidance and research-use-only labeling consistent across the product page, packaging and any accompanying literature.
How Selank's chemistry shapes the analytical data
Because Selank has no tryptophan, tyrosine or phenylalanine, it absorbs UV light only through its peptide bonds, so HPLC detection is done near 214 nm rather than 280 nm. A COA that shows a 280 nm trace for this peptide would show almost nothing, so the wavelength stated is a quick sanity check on whether the report was generated for this compound. Equally, a seven-residue polar peptide elutes early on reversed-phase columns, so a method with a very steep gradient can compress the main peak together with early impurities and flatter the apparent purity. A gradient that starts at low organic content and rises slowly is what allows near-identical species to separate.
| Signal on the report | Consistent with Selank | Questions to ask |
|---|---|---|
| Detection wavelength | ≈ 214 nm | If only 280 nm is shown, was it this peptide? |
| Main-peak retention | Early–intermediate | Is the main peak resolved from the solvent front? |
| ESI-MS ion | [M+H]+ ≈ 752.9; possibly [M+2H]2+ ≈ 377 | Is the observed mass stated and close to expected? |
| Fragments below the main mass | Few or none | Truncations (e.g., missing a terminal Pro) would appear at lower mass |
The two methods answer different questions, as explained in HPLC vs. mass spectrometry. For this specific compound, see also Selank purity testing.
Why the price floor matters
Producing research-grade Selank involves solid-phase synthesis, multi-pass HPLC purification, mass spec confirmation and lyophilization, and each step has a real cost. Pricing that sits well below the market range for a heptapeptide of this purity tier is a signal, not a bargain; the most common shortcuts are skipping mass spec confirmation or accepting lower-purity material to cut purification time. That doesn't mean the highest price is automatically the best-documented product, but a price with no plausible relationship to the underlying production cost is worth questioning before it's worth ordering. For a broader list of warning signs, see red flags when buying research peptides.
Evaluating a supplier's research content
Because Selank's literature base is comparatively thin in English-language sources, the quality of a supplier's own educational material is a reasonable proxy for how carefully they've engaged with the compound. Look for content that cites primary literature rather than paraphrasing other retail sites, acknowledges open questions in the mechanism rather than overstating certainty, and keeps research-use framing consistent rather than treating it as fine-print boilerplate. For proposed mechanisms and reported preclinical findings, see V8's Selank research overview; for a neighboring compound that is often discussed alongside it, see Selank vs. Semax.
Where to buy documented Selank
V8 Peptides supplies Selank as a lyophilized powder with batch documentation covering HPLC purity and identity. The product page, Selank research vial, lists a 10 mg size, the formula and sequence above, ≥98% HPLC purity, and a sealed clear glass vial. The page states that batch-specific analytical documentation is published on the site, and lots can be looked up on the COA page; where a certificate for a given lot is not yet posted, the page says so, which is worth checking before purchase. For a general framework on evaluating any research peptide supplier, see the supplier checklist and vetting a research peptide supplier.
A short pre-purchase routine
Before committing to any Selank order, a lab can work through a five-step routine. First, read the product page for the stated purity, size and form, and note exactly what is promised. Second, find the certificate for the current lot and read the chromatogram itself rather than the summary line; check the wavelength, the gradient and whether small peaks are integrated. Third, compare the observed mass with the expected value near 752 Da. Fourth, confirm that the labeling, packaging and article text all say the same thing about research-only use. Fifth, keep copies of all of it with the experiment record. Spending ten minutes on this routine is far cheaper than discovering after weeks of assays that the material was not what the label said, and it makes any later comparison between lots straightforward.
Receiving, storage and bench preparation
On arrival, check that the vial is sealed, the label matches the order and the lot number matches the documentation, then refrigerate. The V8 page specifies 2–8 °C for storage, or −20 °C for the long term, protected from heat, moisture and light; see storing research peptides and how research peptides are shipped. For preparing solutions, work in concentration terms: 10 mg of peptide in 2 mL of diluent is 5 mg/mL, and in 5 mL it is 2 mg/mL. The reconstitution calculator does this arithmetic, and the general procedure is in how to reconstitute a lyophilized peptide. Record the preparation date and aliquot to avoid repeated freeze-thaw cycles.
Research Use Only. For laboratory research use only; not for human consumption. Not for veterinary or diagnostic purposes. This article is research education, not usage guidance.
Where to buy Selank: FAQ
What is the expected molecular weight of Selank?
About 751.9 Da, from the formula C33H57N11O9. In positive-mode electrospray mass spectrometry the singly protonated ion appears near m/z 752.9.
Why does Selank need detection near 214 nm?
It has no aromatic residues, so only the peptide bonds absorb meaningfully. A 280 nm trace would show little signal for a pure sample.
What purity and size does V8 list for Selank?
The product page lists a 10 mg lyophilized vial at ≥98% HPLC purity.
Is HPLC purity enough to verify the product?
No. It shows how much of the sample elutes as one peak. Mass spectrometry confirms that the peak is the seven-residue sequence, and the lot number links the result to the vial.
Why does a cheap listing deserve questions?
Synthesis, purification, mass-spec confirmation and lyophilization all cost money. A price far below the market range suggests one of those steps was reduced.
How do I confirm the COA belongs to my vial?
Compare the lot number on the vial with the one on the certificate and check the COA page. A mismatch means the documentation is not linked to the product.
Is Selank the same as Semax?
No. They are different peptides with different sequences, studied in overlapping research areas. See the Selank vs. Semax comparison for the distinction.
How should Selank be stored?
As supplied, refrigerate at 2–8 °C, or −20 °C for long-term storage, away from heat, moisture and light, per the product page.