--- title: "What is the molecular formula of retatrutide? | Sable Peptides" description: "Retatrutide has the molecular formula C221H342N46O68. The corresponding molecular weight is 4731.3 g/mol. CAS Registry Number 2381089-83-2." canonical: https://www.sablepeptides.co.uk/questions/retatrutide-molecular-formula publisher: Sable Peptides Limited (UK company 17488610) note: Research use only. Not for human or veterinary use. --- # What is the molecular formula of retatrutide? Retatrutide has the molecular formula C221H342N46O68. The corresponding molecular weight is 4731.3 g/mol. CAS Registry Number 2381089-83-2. Synonyms include LY3437943. The expected mass for identity confirmation by mass spectrometry is derived from this formula. Sable's release specification is ≥99% by HPLC with identity confirmed against the expected mass. Formula. C221H342N46O68. Sequence. H-Tyr-Aib-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Ile-αMeLeu-Leu-Asp-Lys-Lys(N6-{2-\[2-(2-{\[N-(19-carboxynonadecanoyl)-L-γ-glutamyl\]amino}ethoxy)ethoxy\]acetyl})-Ala-Gln-Aib-Ala-Phe-Ile-Glu-Tyr-Leu-Leu-Glu-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH2 (Lys side chain as named in WHO Proposed INN List 128, WHO Drug Information Vol. 36 No. 4, 2022, p. 1051) Analytical note. The expected mass for identity confirmation by mass spectrometry is derived from this formula. Sable's release specification is ≥99% by HPLC with identity confirmed against the expected mass (quality page). Research use only. Not a medicine. Not for human or veterinary use. ## Sources - [https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-(inn)/pl128.pdf](https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-\(inn\)/pl128.pdf) - [https://pubchem.ncbi.nlm.nih.gov/#query=retatrutide](https://pubchem.ncbi.nlm.nih.gov/#query=retatrutide) ## Retatrutide: reference facts 3 Retatrutide values, each linked to its public source; see the [Retatrutide reference page](/ref/retatrutide). | Synonyms | LY3437943 (pubchem.ncbi.nlm.nih.gov) | | --- | --- | | Compound class | peptide (lipidated) (pubchem.ncbi.nlm.nih.gov) | | Storage (lyophilised) | -20 °C, dry, protected from light (sigmaaldrich.com) | ## Sizes and prices at Sable | Vial | Price | Per mg | UK same-size check (2026-10-16) | | --- | --- | --- | --- | | 5 mg | £16.93 | £3.39 | lowest other £20.95 across 2 UK sellers | | 10 mg | £24.99 | £2.50 | lowest other £51.99 across 2 UK sellers | | 15 mg | £37.99 | £2.53 | lowest other £85.00 across 1 UK sellers | | 20 mg | £48.99 | £2.45 | lowest other £93.99 across 2 UK sellers | | 30 mg | £66.99 | £2.23 | lowest other £85.00 across 4 UK sellers | | 40 mg | £88.99 | £2.22 | no same-size match | | 50 mg | £108.99 | £2.18 | no same-size match | | 60 mg | £128.99 | £2.15 | no same-size match | Multi-vial pricing on the same item: 3+ vials 10% off, 5+ vials 15% off, 10+ vials 20% off. Every lot has a certificate of analysis: [CoA library](/coa). ## Typical analytical method | HPLC column | C18 reversed-phase (300 A pore, C4/C8 suitable for large/lipidated) | | --- | --- | | Mobile phase | A: water + 0.1% TFA; B: acetonitrile + 0.1% TFA; linear gradient (e.g. 5-65% B over 20-30 min) | | Detection | 214-220 nm (peptide bond) and 280 nm (Trp/Tyr present) | General literature method. The lot CoA records the method actually used. [How to read an HPLC chromatogram](/learn/how-to-read-an-hplc-chromatogram). ## Related questions - [What is the molecular weight of retatrutide?](/questions/retatrutide-molecular-weight) - [What is the amino acid sequence of retatrutide?](/questions/retatrutide-sequence) - [What does Retatrutide dissolve in?](/questions/retatrutide-solubility) - [How stable is lyophilised Retatrutide?](/questions/retatrutide-stability-lyophilised) ## Lyophilised storage on file: Retatrutide From the Sable storage reference (lyophilised material only; temperature, light, moisture). Literature basis is linked per row. See [peptide storage](/learn/peptide-storage-and-solubility). | Compound | Lyophilised storage | Light / notes | | --- | --- | --- | | Retatrutide | -20 C long term (-80 C acceptable), sealed and desiccated; 2-8 C for weeks | protect from light; no specific sequence liabilities identified from sequence data on file (source) | ## Typical analytical method: Retatrutide Reference HPLC and MS conditions from the Sable analytical-methods file; a lot's CoA states the method actually used. See [how to read a CoA](/guides/how-to-read-a-coa). | Compound | HPLC column / detection | MS / expected ion | | --- | --- | --- | | Retatrutide | C18 reversed-phase (300 A pore, C4/C8 suitable for large/lipidated); 214-220 nm (peptide bond) and 280 nm (Trp/Tyr present) | ESI-MS (positive mode); LC-MS for identity; [M+3H]3+ ~1578.1; [M+4H]4+ ~1183.8; [M+5H]5+ ~947.3; [M+6H]6+ ~789.6 | Research use only. Not a medicine. Not for human or veterinary use.