Quick answer: A Selank COA should show three separate things: identity confirmed by mass spectrometry, purity measured by HPLC, and the amount of peptide in the vial. A high purity number alone does not confirm the first or the third. This article explains what each line should look like for Selank specifically.
What is in the Selank 20mg vial?
Our Selank 20mg is a synthetic heptapeptide, meaning a chain of seven amino acids. The product page describes it as developed from a tuftsin-based structure and supplied as a lyophilized (freeze-dried) powder, 20mg per vial, for laboratory research use only. Storage is listed as refrigerated and protected from light.
The same compound is also listed as Selank 5mg. The vial size changes the amount of powder, not the tests that should apply to it.
How is Selank identified by mass?
Mass spectrometry weighs the molecules in a sample. If the peptide is correct, the measured mass matches the mass calculated from its sequence. Selank is generally reported as Thr-Lys-Pro-Arg-Pro-Gly-Pro, with a formula of C33H57N11O9. The product page does not list these identifiers, so treat the figures below as our calculation from that sequence, not as values from the page:
- Average molecular weight: about 751.9 g/mol
- Monoisotopic mass: about 751.4
- Singly charged ion ([M+H]+): about 752.4
- Doubly charged ion ([M+2H]2+): about 376.7
Selank contains lysine and arginine, which carry positive charge, so a doubly charged peak is common. If a COA lists only a peak far from these values, the identity is not confirmed. Our article on why mass matters more than purity explains the logic in more depth.
What does HPLC purity tell you about Selank?
HPLC (high-performance liquid chromatography) separates a sample into components and shows each as a peak. Purity is the target peak's share of the total peak area. Selank is a small, strongly basic peptide that tends to come off a standard reversed-phase column early, so the method matters. A good chromatogram shows a clean, well-separated main peak, not one crowded against the solvent front.
On the COA, look for the chromatogram itself, not just the percentage. Also check the batch number, test date and detection wavelength.
Does 20mg on the label mean 20mg of Selank?
Not automatically. Freeze-dried peptide contains the peptide plus residual water and counter-ions, often trifluoroacetate (TFA) left from purification. Selank's basic residues attract both. Purity by HPLC says nothing about this, and mass spectrometry cannot measure quantity. Content is usually established by a separate method, such as amino acid analysis or quantitative HPLC against a reference standard.
So when a COA shows a purity figure but no content or net peptide line, one of the three questions is unanswered. The page says testing is HPLC and/or mass spectrometry, so check which methods your batch's COA actually reports.
Which impurities and stability issues matter for Selank?
| Issue | Why it applies to Selank | Which test shows it |
|---|---|---|
| Missing amino acids (deletion sequences) | The sequence has three prolines, and coupling steps around proline can be less efficient | Mass spectrometry, then HPLC for the share |
| Leftover protecting groups | Arginine and lysine side chains are protected during synthesis and must be fully removed | Mass spectrometry (extra mass on a peak) |
| Water and TFA content | Basic residues hold counter-ions; powder absorbs moisture | Content or net peptide analysis |
| Oxidation | Lower concern, since the sequence has no methionine, cysteine or tryptophan | HPLC and mass shift of +16 |
The sequence has fewer chemically fragile residues than many peptides, but moisture and light still matter, which is why the page lists refrigerated storage away from light. For background, see our explainer on lyophilization.
What should the Selank COA image show?
When you open the COA for your batch, work through this list:
- Compound name and vial size match the product.
- The lot number matches your vial.
- A measured mass close to the calculated values above.
- An HPLC chromatogram with a single dominant peak and a stated purity.
- A content or net peptide line, or a clear statement that it was not measured.
- A test date and the name of the testing laboratory.
For a general walkthrough, use our line-by-line COA guide. Our peptides are synthesized at a WHO/GMP and ISO 9001 certified laboratory in California.
Frequently asked questions
Is a high HPLC purity enough to trust a Selank vial?
No. Purity shows how clean the main peak is, not whether that peak is Selank or how much peptide the vial holds. You need the mass result and a content figure as well.
What does TFA mean on a Selank COA?
TFA is trifluoroacetic acid, used during peptide purification. It can remain as a salt attached to the peptide, so it adds to the powder's weight without being peptide.
Can mass spectrometry tell me how much Selank is in the vial?
No. It confirms what the molecule is, not how much of it is present. Quantity needs a different method.
Do Selank 5mg and 20mg vials get different tests?
The same identity, purity and content checks apply to both. Only the fill amount differs.
Why does the lot number on the COA matter?
Results describe one production batch. A COA from a different lot says nothing certain about the vial in your hands.
Every lot we sell has a Certificate of Analysis you can read before you order. Questions before you buy? Our team is in Chandler, Arizona: (888) 745-1505 or our contact page.
View Selank | 20mgAll products sold by BioPure Peptides are intended strictly for in-vitro laboratory and research use only. They are not for human or animal consumption. These statements have not been evaluated by the U.S. Food and Drug Administration, and these products are not intended to diagnose, treat, cure, or prevent any disease.