Retatrutide purity testing: how Pure Helix lots are analysed
Every retatrutide lot we release is tested by an independent laboratory for purity and identity, and the result is published as a lot-level certificate rather than as a marketing number.
- Last scientific review
- September 2026
- Published by
- Pure Helix
What is measured, and by which method
| Question | Method | What the result establishes |
|---|---|---|
| Is the main peak dominant? | Reversed-phase HPLC, UV 214 nm | Area-percent purity relative to all detected peaks |
| Is it the right molecule? | LC-MS | Observed mass matches the calculated mass for the sequence |
| How much is in the vial? | Quantitative content assay | Reported peptide content in mg per vial |
Purity and content are different measurements. A high area-percent purity says nothing about fill weight, and a correct fill weight says nothing about the proportion of related substances.
Published results for current retatrutide lots
| Fill weight | Lot | Purity (HPLC area %) | Reported content | Assay date |
|---|---|---|---|---|
| 10 mg | PH260501 | 99.9% | 11.83 mg | 1 June 2026 |
| 20 mg | PH260502 | 99.9% | 20.83 mg | 1 June 2026 |
| 30 mg | PH260503 | 99.9% | 31.03 mg | 31 May 2026 |
Each lot has its own certificate page carrying the signed source document. Reported content exceeding the nominal fill weight reflects overage in the fill, and is a measured value from the assay, not a claim about potency.
Why retatrutide is a demanding purity separation
The fatty-diacid modification makes the molecule strongly retained on C18, so a gradient tuned for unmodified peptides will compress the main peak against late-eluting related substances. The related substances that matter most for a lipidated 39-mer are deletion sequences differing by one residue, oxidation products and deamidation products — species close enough in hydrophobicity that a shallow, well-resolved gradient is required to separate them.
This is why an area-percent figure is only meaningful with its method attached, and why comparing a purity number between suppliers without the chromatographic conditions is not a comparison at all.
What these tests do not establish
- They do not establish sterility or endotoxin status; those are separate tests that we do not claim.
- They do not establish biological activity — potency at any receptor is a separate assay.
- They do not establish stability over time; a certificate is a measurement on a date, and storage conditions govern what happens after it.
- They do not make the material suitable for human or veterinary use.
Research use
Pure Helix supplies materials for laboratory research use only. Nothing on this page is medical advice, and none of the material described is for human or veterinary use.
Primary literature and standards
- ICH Q2(R2) — Validation of Analytical Procedures
- Mant CT, Hodges RS. Analysis of peptides by HPLC. Methods in Enzymology.
- Manning MC et al. Stability of protein pharmaceuticals: an update. Pharm Res. 2010.Degradation chemistry underlying the related substances a purity method must resolve.
Reference materials and documentation
Related reading
- Analytical TestingHPLC peptide purity: what the percentage actually measuresPurity by HPLC is an area-percent measurement, not a statement that a vial is 99% target compound by mass. The distinction changes how the number should be used at the bench.
- Analytical TestingLC-MS peptide identity: mass confirmation versus purityHPLC asks how much of the detected material is one species. Mass spectrometry asks whether that species is the molecule on the label. Neither substitutes for the other.
- Analytical TestingHow to read a retatrutide certificate of analysisA certificate is only useful if it is traceable to the specific vial. This page walks the fields on a real retatrutide certificate and shows what each one does and does not prove.
- Compound ResearchRetatrutide research hubRetatrutide is a synthetic 39-residue peptide reported to engage three incretin-family receptors. This hub collects the mechanism pages, the molecular reference record and the lot documentation in one place.