Glowing teal mass spectrometry peak pattern on a dark navy background, representing analytical identification of PT-141 name variants and mass.
Mindful Research

PT-141 Name Variants (Peptide 141, PT141): Verifying Identity by CAS and Mass Spec

By: Mindful Research Team2 min read

Key takeaways

  • Peptide 141, PT141, and PT-141 are name variants for bremelanotide, CAS 189691-06-3.
  • Verify identity by CAS number and PubChem CID 9941379, not by the label name.
  • Expected formula C50H68N14O10; [M+H]+ about 1025.53 and [M+2H]2+ about 513.27.
  • Melanotan II differs by only 0.98 Da, so mass accuracy matters.
  • For in vitro research use only.

"Peptide 141", "PT141", and "PT-141" are all names for the same research peptide, bremelanotide (CAS 189691-06-3), and the reliable way to verify that a vial is peptide 141 is by CAS number, molecular formula C50H68N14O10, and mass-spectrometry identity. This guide explains the naming variants and the analytical checks that confirm them for PT-141.

What do the PT-141 name variants mean?

Name seen What it refers to
PT-141 Standard research designation
PT141 Same designation without the hyphen
Peptide 141 Informal search and catalog variant of PT-141
Bremelanotide Generic chemical name
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH Sequence notation

Naming alone proves nothing: a label can say anything. Identity has to be shown by data tied to the lot.

How do you verify peptide 141 by CAS number?

The CAS Registry Number for bremelanotide is 189691-06-3, and the PubChem record is CID 9941379. Match both against the product label and the certificate of analysis. The closely related Melanotan II has a different CAS number (121062-08-6), so a mismatch is an immediate red flag.

How do you verify it by mass spectrometry?

Electrospray mass spectrometry should show ions consistent with the molecular formula C50H68N14O10 (monoisotopic mass about 1024.52 Da).

Ion Expected m/z (approx.)
[M+H]+ 1025.53
[M+2H]2+ 513.27
[M+3H]3+ 342.52

Because Melanotan II differs from PT-141 by only 0.98 Da at the C-terminus (amide versus free acid), a high-resolution measurement is what separates the two. The side-by-side comparison is in PT-141 vs Melanotan II.

What should the certificate of analysis include?

A lot number, an HPLC chromatogram with percent purity, the MS result, and the CAS number. See Sourcing PT-141 as a research material for the full checklist, or the structural background in the PT-141 structure and receptor profile guide.

Find a COA: every PT-141 batch report is listed in our certificate of analysis library, searchable by batch number.

Related research guides

Research-use note

All materials discussed are supplied for in vitro laboratory research use only, and are not for human or animal use.

Frequently asked questions

Is peptide 141 the same as PT-141?

Yes. Peptide 141, PT141, and PT-141 are name variants for the same research peptide, bremelanotide, CAS 189691-06-3. View PT-141

What CAS number identifies it?

CAS 189691-06-3, with PubChem CID 9941379.

What mass should mass spectrometry show?

Monoisotopic mass of about 1024.52 Da for C50H68N14O10, giving [M+H]+ near 1025.53 and [M+2H]2+ near 513.27.

How is it distinguished from Melanotan II?

Melanotan II differs by 0.98 Da at the C-terminus, so a high-resolution mass measurement and CAS check separate them. PT-141 vs Melanotan II

Is it for human or animal use?

No. It is supplied for in vitro laboratory research use only.

Continue reading

Two research vials of lyophilized peptide powder beside a volumetric flask and pipette, illustrating in vitro stock concentration preparationBPC-157, TB-500 Blend: Vial Reconstitution and Stock Concentration Math (In Vitro) Reconstituting the 10 mg / 10 mg BPC-157, TB-500 vial in a single aqueous volume gives each peptide its own molar concentration—both sit at... Scientist in lab coat reviewing a two-peak HPLC chromatogram to verify a two-component peptide blend for in vitro researchSourcing a BPC-157, TB-500 Blend: Two-Component COA and Ratio Verification A credible BPC-157, TB-500 blend COA must confirm both peptides independently—each resolved by mass spectrometry at its expected mass and each quantified... 3D render of two peptide chains side by side, illustrating blend composition and ratio studied in parallel in vitroBPC-157, TB-500 Blend Composition and Ratio: Why Two Peptides Are Studied in Parallel (In Vitro) In the BPC-157, TB-500 blend the two peptides are present at a fixed 1:1 mass ratio (10 mg each in current lots), and...