---
title: "What is the molecular weight of retatrutide? | Sable Peptides"
description: "The molecular weight of Retatrutide is 4731.3 g/mol on the registry record used for identity. The molecular formula is C221H342N46O68."
canonical: https://www.sablepeptides.co.uk/questions/retatrutide-molecular-weight
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# What is the molecular weight of retatrutide?

The molecular weight of Retatrutide is 4731.3 g/mol on the registry record used for identity. The molecular formula is C221H342N46O68. CAS Registry Number 2381089-83-2. It is classed as a peptide (lipidated). Synonyms include LY3437943. Laboratories use this mass when confirming identity by mass spectrometry.

Mass. The expected average mass for identity confirmation is 4731.3 g/mol.

Formula. C221H342N46O68.

Analytical note. 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://rest.kegg.jp/get/D12430](https://rest.kegg.jp/get/D12430)
-   [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 formula of retatrutide?](/questions/retatrutide-molecular-formula)
-   [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.