To check a retatrutide supplier, ask for one document: a certificate for the exact lot you would receive, showing a mass spectrum against 4,731 Da, an HPLC chromatogram with its method and date, and a stated net peptide content. Reta is lab shorthand for retatrutide (LY3437943). That check decides where to buy retatrutide.
- Reta peptide means retatrutide, development code LY3437943, an investigational triple agonist at the GIP, GLP-1 and glucagon receptors.
- LabFirst lists retatrutide in 8 sizes from $80 (5 mg) to $214 (60 mg); the 60 mg vial is cheapest per mg at $3.57, read November 4, 2026.
- The identity reference is PubChem CID 171390338: C221H342N46O68, average molecular weight 4,731, monoisotopic mass 4,728.47.
- No approved medicine contains retatrutide, and there is no USP or Ph. Eur. monograph or official reference standard for it; the developer plans an FDA submission in the first quarter of 2027.
- Deconvoluted ESI-MS separates retatrutide from tirzepatide, semaglutide and liraglutide easily, but cannot detect sequence scrambling or racemization.
- HPLC area percent purity and net peptide content are different numbers, and only the second tells you how much peptide a vial holds.
- Each LabFirst lot is tested by an independent laboratory and the laboratory's own report is published for that lot at /coa/.
The short version for a buyer
Retatrutide peptide is bought on paperwork, because the powder in two vials can look identical and be different molecules. A supplier worth ordering from can show, before money moves, a certificate for the specific lot: a mass spectrum with the theoretical and observed mass printed, an HPLC chromatogram with its method conditions and a run date, a stated net peptide content and a named counterion. A supplier who cannot is relaying an order to an intermediary whose lot records you will never see.
"Reta" is community shorthand for retatrutide, developer code LY3437943, a synthetic 39-residue peptide that activates the GIP, GLP-1 and glucagon receptors. It is investigational: no approved medicine contains it as of November 4, 2026. This page covers what the name means, the sizes and price per mg LabFirst lists, what a certificate has to carry, how to verify a lot, what drives the price, storage of the sealed vial, and the regulatory position. It gives no guidance on use of any kind.
- Lot identifier and analysis date: without these, nothing below counts
- Mass spectrum with theoretical and observed mass
- RP-HPLC chromatogram with method conditions, rather than a bare percentage
- Net peptide content and counterion identity
- Water content and stated fill weight tolerance
- Independent third-party confirmation, published per lot
What does reta peptide mean, and why write the full name?
Reta is a nickname, and nicknames cause mix-ups. It has no standing as a chemical name and it resolves ambiguously the moment someone else reads the notebook. The compound behind it is retatrutide, first described in Cell Metabolism in 2022 by Coskun and colleagues under the Eli Lilly code LY3437943, as a single peptide agonist at three receptors: the glucose-dependent insulinotropic polypeptide receptor, the glucagon-like peptide-1 receptor and the glucagon receptor.
Names in circulation for the same material:
- Retatrutide: the INN, and the term to use in any record.
- LY3437943: the development code, still the most searchable identifier in the primary literature.
- Triple agonist, GGG tri-agonist, GLP-3 and reta: informal names, worth translating on receipt. Our GLP-3 retatrutide guide explains why the first of those names no real hormone.
PubChem files it under CID 171390338 with the formula C221H342N46O68, an average molecular weight of 4,731 and a monoisotopic mass of 4,728.47. Those are the numbers a mass spectrometer is checked against. If the material arrives labeled only "reta 10mg", the label itself is the first quality signal, and it is not a good one.
How much does retatrutide peptide cost, and which size is cheapest per mg?
LabFirst lists retatrutide in 8 sizes from $80 to $214 a vial, priced per vial with the per-mg figure beside it so sizes can be compared without arithmetic. The per-mg price falls steeply with size because the vial, stopper, seal, freeze-drying run, label and laboratory test cost the same whatever mass goes in.
| Size | Price | Per mg |
|---|---|---|
| 5 mg | $80 | $16.00 |
| 10 mg | $85 | $8.50 |
| 15 mg | $90 | $6.00 |
| 20 mg | $115 | $5.75 |
| 30 mg | $165 | $5.50 |
| 40 mg | $204 | $5.10 |
| 50 mg | $209 | $4.18 |
| 60 mg (best per mg) | $214 | $3.57 |
Volume tiers are per size, not per basket: ten to nineteen vials of one size take 10% off that line and twenty or more take 15%, and mixed sizes do not combine. USPS Ground Advantage is free on orders over $150 and a flat $15 below it, within the United States only, with same-day dispatch on verified in-stock orders placed before 12 PM Pacific on a business day. A size marked backordered on the retatrutide for sale page joins a waitlist rather than taking money against stock that is not on the shelf.
Compare on cost per milligram of peptide, which is the price per mg corrected by the certificate's net peptide content. The cost per mg tool runs that arithmetic across any two listings and refuses to guess when net content is missing.
What is the structure and physical form of retatrutide?
Retatrutide is a linear 39-residue peptide built on a GIP-analog backbone. It carries two non-coded alpha-aminoisobutyric acid (Aib) residues at positions 2 and 20, alpha-methyl-leucine at position 13, a C20 fatty diacid conjugated through a spacer and linker to the lysine at position 17, and a C-terminal amide; the LC-HRMS literature gives those positions. Where a position assignment matters to your work, take it from the primary publication rather than from an aggregator page.
Two features drive handling. The lipid chain makes the molecule amphiphilic, so it concentrates at air-water interfaces and adsorbs to container surfaces at low concentration. The Aib substitutions resist enzymatic cleavage and do nothing about hydrolysis, deamidation or oxidation, which is a distinction people routinely collapse. Supplied form is a lyophilized cake or powder in a sealed glass vial, as an acetate or trifluoroacetate salt. Which counterion is present is not cosmetic: TFA is a synthesis residue with known effects in cell-based systems, and the salt form belongs on the certificate before the vial ships.
What does a mass spectrum settle, and what does it leave open?
Identity confirmation for a 39-mer rests on electrospray LC-MS. The instrument sees a family of multiply charged ions, deconvolution gives a mass, and that mass is compared with the theoretical value for the stated sequence and salt form. It is a cheap, fast test and it catches the crudest failure in the research-chemical trade, which is a vial containing a different incretin peptide entirely.
| Compound | Approximate average mass | Separation from retatrutide |
|---|---|---|
| Retatrutide | 4,731 Da | reference |
| Tirzepatide | 4,813 Da | about 80 Da, trivially resolved |
| Semaglutide | 4,114 Da | about 600 Da, trivially resolved |
| Liraglutide | 3,751 Da | about 1,000 Da, trivially resolved |
The limits deserve plain statement. A deconvoluted mass does not distinguish sequence isomers, does not detect D-amino acid incorporation from racemization, and will not flag a scrambled sequence of identical composition. A single-residue deletion shifts mass by roughly 60 to 190 Da, which is detectable, but the impurity peak has to be looked for rather than assumed absent. Settling those questions takes a peptide map: enzymatic digest, LC-MS/MS on the fragments, coverage reported against the claimed sequence. Few research suppliers run one. Our guide on how retatrutide identity is confirmed goes further.
What should a retatrutide certificate of analysis show?
Chromatographic purity is measured by reversed-phase HPLC, typically a C18 column with a water and acetonitrile gradient in dilute trifluoroacetic acid, detected at 214 or 220 nm where the amide backbone absorbs. The reported figure is the main peak as a percentage of total integrated peak area. USP General Chapter 621 sets the system suitability expectations that make such a number meaningful; ICH Q2(R2) covers what validating the method involves.
Area percent is relative. It says nothing about how much of the powder is peptide. Net peptide content accounts for counterion, residual water and solvent, and for a lyophilized TFA salt it can sit well below 90 percent of gross mass. A vial sold as 10 mg at 99 percent HPLC purity may hold rather less than 10 mg of peptide, and the certificate is the only place that gets resolved.
| Line item | Method | What it establishes | If absent |
|---|---|---|---|
| Identity | ESI-MS or MALDI-TOF | Observed mass matches theoretical | A substituted compound cannot be excluded |
| Chromatographic purity | RP-HPLC, area % at 214/220 nm | Main peak relative to related substances | The headline percentage is an assertion |
| Net peptide content | Amino acid analysis, UV or nitrogen determination | Peptide mass fraction of the powder | Cost per mg of peptide is unknown |
| Water content | Karl Fischer or loss on drying | Residual moisture | Mass basis and stability both unverified |
| Counterion | Ion chromatography | Acetate or TFA, and how much | Assay interference risk in cell work |
| Related substances | RP-HPLC impurity profile | Deletion, oxidation, truncation peaks | Nothing is known about failure mode |
| Fill weight | Gravimetric, with tolerance | Actual vial contents against label | Every mass figure starts wrong |
A certificate carrying a lot number, an analysis date, the method conditions and an attached chromatogram is a document. A one-page PDF stating "Purity: 99.1%" with no lot, no date and no trace is marketing with a border around it. The retatrutide certificate guide reads a real one field by field.
How do I verify a LabFirst retatrutide lot?
Verification runs through the testing laboratory, not through us. Each lot is sent to an independent laboratory for identity by mass spectrometry, purity by HPLC and net peptide content, and the laboratory's own report is published for that lot at the certificate index and on the product page. Until a lot's report is attached, the product page says "pending verification" against that lot and makes no purity claim; the report goes live the day it arrives.
The lot is printed on the label and encoded in the QR patch on its right-hand side; scanning it opens that lot's record. The product page reads the live stock feed on load, so the lot and certificate state you see when you order is what ships. Our guide on verifying a retatrutide certificate walks through the 60-second check.
What drives the price of retatrutide peptide?
Retatrutide is expensive to make honestly. A 39-residue chain by solid-phase synthesis accumulates deletion and truncation impurities at every coupling, the lipidation step adds a conjugation and a further purification, and the preparative HPLC that pulls a 98 percent fraction out of crude material discards a great deal of it. Yield, not raw material, sets the floor.
| Driver | Effect on price |
|---|---|
| Purity specification | Moving from 95% to 99% can cost more in discarded fractions than the whole synthesis |
| Analytical package | Lot-specific MS plus HPLC plus water and counterion determination is real instrument time |
| Third-party confirmation | An independent laboratory assay per lot adds a fixed cost spread across the lot |
| Salt form and net peptide | Two vials at the same price per gross mg differ in peptide delivered |
| Fill size and vial count | Filling many small vials costs more per mg than fewer large ones |
| Cold chain | Insulated packaging and coolant are per-shipment costs, not per-mg |
Prices far below the market cluster are information. The most common explanations are a lower real purity than claimed, an overstated fill weight, or a different molecule. See shipping for how we package and document temperature-controlled transit.
Checking a supplier of retatrutide: what to ask for before money moves
- Ask for the certificate for the specific lot you would receive, not a representative one.
- Check that it carries a lot identifier, an analysis date, the method conditions and an attached chromatogram.
- Look for a mass spectrum compared with the theoretical mass, 4,731 Da average or 4,728.47 Da monoisotopic.
- Find a stated net peptide content and a named counterion.
- Compare price on cost per milligram of peptide, after the net content correction.
Signals that reliably correlate with problems:
- A certificate with no lot identifier, no analysis date, or a date that predates the synthesis.
- A purity figure with no method conditions and no chromatogram attached.
- Claims of "pharmaceutical grade", "GMP" or "sterile" with no audit reference, no facility name and no sterility or endotoxin data.
- Identical chromatogram images reused across different products.
- Marketing copy that references body composition, trial outcomes or human use in any form; a supplier that writes it is not operating within research-use-only boundaries, and its documentation should be read in that light.
- No named counterion anywhere in the paperwork.
Retatrutide is not a scheduled controlled substance in the United States. That does not make importation frictionless: customs treatment of research chemicals varies, and labeling that fails to state the research-use restriction creates problems at the border rather than solving them.
How should the sealed vial be stored, and what goes in the record?
Held as a sealed, dry, dark solid at minus 20 C or below, retatrutide sits in a slow degradation regime. Moisture is the variable that governs, not the freezer setting. The most common avoidable loss happens when a cold vial is opened in a humid room and the hygroscopic cake takes up condensed water within seconds; let a sealed vial reach room temperature before breaking the seal. The reasoning is set out in the retatrutide storage and stability guide.
The record for each vial carries the lot, the date received, where it was stored and the net peptide content from the certificate. A 10 mg nominal vial at 87 percent net content holds about 8.7 mg of peptide, and the record should say which of those two figures it uses. This page stops at the sealed vial.
What is the regulatory status of retatrutide in 2026?
Investigational. No approved medicine contains retatrutide as of November 4, 2026. The developer announced topline results from two further phase 3 trials in its TRIUMPH program on July 23, 2026 and said it plans to submit the compound to FDA in the first quarter of 2027, once the chemistry, manufacturing and controls package is complete. This page reports no efficacy or endpoint data; the ClinicalTrials.gov register and the developer's releases are the places to read those. Check FDA's approvals databases directly rather than relying on any supplier page, including this one.
Two consequences follow for laboratory buyers. There is no USP or Ph. Eur. monograph and no pharmacopeial reference standard for retatrutide, so every purity figure rests on the supplier's own method and reference material. And an unapproved active ingredient carries no general route into compounded preparations; research-grade material has never been a lawful route to human use at any point. FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. NOT FOR PERSONAL, MEDICAL, DIAGNOSTIC, THERAPEUTIC, OR RECREATIONAL USE.
Bottom line
Reta is retatrutide, LY3437943, an investigational peptide with no approved medicine and no pharmacopeial reference standard. Buy it against a lot certificate that shows a mass spectrum, an HPLC chromatogram with method conditions, an analysis date and net peptide content. Compare on cost per milligram of peptide; at LabFirst the 60 mg vial is cheapest per mg and the 5 mg vial is the sensible first order while a lot is being qualified. Treat a price far below the market as information.
What is Retatrutide studied for?
Published research on Retatrutide investigates the areas below, which is a different question from what Retatrutide will do for anyone, a claim about a living system that nothing on this site is sold for.
What it is. An experimental peptide that works on three incretin receptors at once.
What the research looks at. It shows up in clinical-stage metabolic research under the developer code LY3437943. The published work is about how it behaves at those receptors, how the effect changes with the amount given, and the measurements the sponsor registered its trials to take.
How it is thought to work. It switches on three receptors at the same time: GIP, GLP-1 and glucagon. Everything before it in this family worked on one or two. Hitting all three is why researchers treat it as its own kind of compound rather than a stronger version of what already existed.
What is not established. No regulator has approved it for anything, anywhere. It is still experimental, and nobody has made a finding about whether it is safe, whether it works, or whether it is fit for any purpose outside a registered trial.
The full record, including the certificate for the lot in stock, is on the Retatrutide product page.
Common questions
Where can I buy retatrutide peptide for research?
How much does retatrutide peptide cost?
Is reta peptide the same thing as retatrutide?
What single document matters most when buying retatrutide?
Why does 99 percent purity not mean 99 percent peptide?
Can LC-MS alone confirm a vial contains retatrutide?
Is retatrutide FDA approved?
Why do retatrutide prices vary so widely between suppliers?
Published certificates for Retatrutide
Every figure below is read from a report the laboratory issued for that lot; each page carries the PDF and the lab's own verification link.
More laboratory guides
Sources
- Coskun et al., LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist, Cell Metabolism, 2022. First full pharmacological description of LY3437943 as a triple GIP, GLP-1 and glucagon receptor agonist; supports the nomenclature, receptor targets and development-code equivalence stated here.
- PubChem compound record 171390338 (retatrutide). Public compound record: formula C221H342N46O68, average molecular weight 4,731, monoisotopic mass 4,728.47, read November 4, 2026.
- Detection and Excretion Profile of Retatrutide by LC-HRMS, Rapid Communications in Mass Spectrometry. Residue-level structure: 39-residue GIP-derived backbone, Aib at 2 and 20, alpha-methyl-leucine at 13, C20 diacid on Lys17, amidated C-terminus.
- USP General Chapter <621>, Chromatography. Establishes system suitability, resolution and integration expectations that make a reported RP-HPLC area percent figure interpretable rather than decorative.
- ICH Q2(R2), Validation of Analytical Procedures (2023) . Defines what validating an identity or purity method requires, and is the reference point for judging whether a supplier method has been validated at all.
- Developer press release, July 23, 2026: retatrutide phase 3 TRIUMPH topline results and planned FDA submission. Status only: two additional phase 3 trials read out July 23, 2026, and the developer plans to submit retatrutide to FDA in the first quarter of 2027. No trial outcomes are repeated on this page.
