Melanotan-II is a cyclic peptide, and confirming both its sequence and its cyclization state is part of verifying a lot before research use.
Reversed-phase HPLC
HPLC separates correctly cyclized melanotan-II from linear (uncyclized) intermediate and other synthesis byproducts, with purity read per understanding HPLC purity.
Mass spectrometry for identity
Mass spectrometry confirms molecular identity and can help flag whether cyclization is complete, since a linear precursor carries slightly different mass than the finished cyclic peptide described in the chemistry article — see HPLC vs. mass spectrometry.
Why this matters for a broad-receptor agonist
Because melanotan-II's research profile depends on engaging multiple melanocortin receptors as detailed in its mechanism of action, an incompletely cyclized or impure lot could produce a receptor-engagement pattern that differs from the more MC4R-focused PT-141 for reasons unrelated to the intended comparison.
Documentation to expect
A lot-specific certificate of analysis with HPLC purity and mass-spec identity — see how to read a CoA.
Product page: Melanotan-II research vials.
Research Use Only. Supplied strictly for laboratory research and development — not for human or veterinary use, consumption, or any therapeutic or diagnostic purpose. This article is research education, not usage guidance.