Quick answer: A Melanotan 2 certificate of analysis should show three things: a measured mass that matches the molecular formula C₅₀H₆₉N₁₅O₉, a purity figure from HPLC, and a content figure for the vial. Because Melanotan 2 is a ring-shaped peptide with a few look-alike impurities, it is worth knowing what each test can and cannot prove.
Why is Melanotan 2 different to test?
Melanotan 2 (also written Melanotan II, MT-II or MT2) is a cyclic heptapeptide, meaning seven amino acids joined into a ring by a lactam bridge. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂. In published laboratory research it is described as a non-selective agonist at the melanocortin receptors MC1R, MC3R, MC4R and MC5R.
Three features of that structure matter for quality testing:
- The ring. If the ring does not close during synthesis, the open-chain version stays in the powder.
- D-Phenylalanine. This is the mirror-image form of a common amino acid. The wrong form has the same mass.
- Tryptophan. This amino acid is easily oxidized, which creates a heavier by-product.
What is in the Melanotan 2 vial?
Our Melanotan 2 (MT2) 10mg vial holds the synthetic peptide as a freeze-dried powder. For why peptides ship that way, see our lyophilization guide. It is sold for laboratory research use only.
| Identifier | Value |
|---|---|
| CAS number | 121062-08-6 |
| Molecular formula | C₅₀H₆₉N₁₅O₉ |
| Molecular weight | ~1024.18 g/mol |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ |
How is identity confirmed by mass?
Mass spectrometry weighs the molecules in the sample. Calculated from the formula, the singly charged ion sits near 1024.5, and the doubly charged ion near 512.8. Your COA may list either value, or both. The reported mass should land very close to one of these.
Mass also exposes the most common problems. Compare the main peak against these shifts:
| Mass seen | Likely meaning |
|---|---|
| About 18 units higher | Open-chain peptide where the ring never closed |
| About 16 units higher | Oxidized tryptophan |
| About double the expected value | Two peptide molecules joined together |
| Lower by a whole amino acid | A deletion sequence from incomplete synthesis |
Our article on why mass matters more than purity explains the same logic for another compound.
What can HPLC purity tell you?
HPLC separates the sample into peaks and reports the main peak as a percentage of the total. It shows how clean the powder is. It does not show what the main peak is.
It also has a blind spot here. A version made with the wrong D-Phe form, or with a look-alike amino acid in place of norleucine, has the same mass as the real peptide and can elute very close to it. A routine COA cannot fully rule those out. Reliable identity therefore depends on both tests together and on controlled synthesis.
What does content per vial mean?
Powder weight is not the same as peptide weight. A vial also holds water and counter-ions left from purification. Content testing measures how much actual peptide is present.
A useful COA states the method used and gives the result in milligrams per vial against the labeled amount. A COA with purity and mass but no content line leaves that question open.
What should you check on the COA itself?
- The product name and batch number match the vial label.
- The tested mass is a measured value, not just the theoretical one.
- The chromatogram is included, not only a purity percentage.
- A test date, a named laboratory and a content result are shown.
For a full walk-through of every line, read our line-by-line COA guide.
Frequently asked questions
Why does a Melanotan 2 COA sometimes list two mass values?
The instrument can detect the molecule with one or two added charges, which gives two readings of the same compound. Both should correspond to a mass of about 1024.
Does 99% HPLC purity prove the vial is Melanotan 2?
No. HPLC measures cleanliness, not identity. You need the mass result alongside it.
Should the batch number on the COA match my vial?
Yes. A COA only describes the lot it was run on, so the numbers must match exactly.
Why can the labeled 10mg differ from measured peptide content?
Water and counter-ions add weight to the powder without being peptide. That is why content is tested separately.
What if a COA gives purity but no chromatogram?
Treat it as incomplete. The trace lets a reader see shoulders, split peaks or extra impurities that one percentage hides.
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 Melanotan 2 (MT2) | 10mgAll 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.