A certificate of analysis (COA) is a laboratory document. It is not an approval, a safety finding or a guarantee. Whether it helps you depends on which question the test was built to answer, and whether the report can be tied to the exact sample in front of you.
Eloralintide is an investigational amylin receptor agonist from Eli Lilly and is not approved by any regulator. This guide is about reading analytical evidence. It gives no dosing, preparation or use guidance.
Key takeaways
- Purity, quantity, identity and structure are four separate questions. One number cannot answer all four.
- A purity percentage describes a chromatogram. It does not tell you how many milligrams are present.
- A matching mass is necessary for identity but is not enough on its own to confirm the structure.
- A report only means something if it is genuine, complete and linked to the sample by batch and chain of custody.
- Effects, lack of effects and how a powder dissolves cannot authenticate a sample.
Four questions, four different tests
| Question | Test often used | What it can show | What it cannot show on its own |
|---|---|---|---|
| Is the main peak clean? | Reversed-phase HPLC with UV detection | Share of the detector signal that belongs to the main peak, under that one method | The amount of peptide, what the main peak is, or anything that does not absorb UV or hides under the peak |
| How much peptide is there? | Calibrated quantitative assay against a reference standard | An amount estimate, with the uncertainty of the calibration | Identity, or whether the reference standard itself was correct |
| Is it the right molecule? | LC-HRMS (accurate intact mass) | Whether the measured mass fits the expected molecule | Which atoms are connected where, or the difference between isomers that share a mass |
| Is the structure right? | MS/MS fragmentation, and NMR (1H plus 2D experiments such as HSQC and COSY) | Evidence for parts of the sequence, modification sites and connectivity, if the data are assigned and interpreted | Anything, if the spectrum is not assigned or compared with a trusted reference |
| Is it free of endotoxin and microbes? | Endotoxin assay; sterility test | Result under a defined method and sample | Peptide identity, purity or amount |
Each row is a different measurement. A report that lists “99%” in one row has told you nothing about the other rows.
Purity is a share of a chromatogram
In HPLC the sample is pushed through a column and a detector records a signal over time. The report integrates each peak and states what share of the total signal belongs to the main one.
That share depends on the method: the wavelength, the gradient, the column and how the baseline was set. A different method can split or merge peaks and change the figure. Material that does not absorb at the chosen wavelength, such as many salts, water and some excipients, does not appear at all.
So 99% purity by HPLC means “about 99% of what this method detected was in the main peak.” It does not mean 99% of the vial is Eloralintide, and it does not say the main peak is Eloralintide.
Quantity needs a method and a calibration
A milligram figure only has meaning if the report says how it was obtained: which reference standard, what calibration curve, and whether the result is peptide content or total powder mass. Freeze-dried peptide powder also carries water and counterions, which is why “net peptide content” and “gross weight” can differ.
Measured amounts can differ from a label for several reasons, including how the vial was filled, the calibration, and how content was defined. A report on its own rarely lets you tell which. Treat a quantity result as one measurement of one sample under one method.
Identity: mass is necessary, not sufficient
Accurate intact mass (LC-HRMS) tells you whether the molecule’s weight fits the expected formula, usually to a few parts per million. That is a strong filter. It does not show how the atoms are arranged.
Two species can share a mass and differ in structure. Eloralintide’s published design has a methylene thioacetal bridge in place of the native disulfide (Briere et al., 2025). By simple arithmetic a methylene bridge adds about one CH2 unit (roughly 14 Da) compared with a disulfide, so intact mass can tell those two apart. Intact mass cannot show whether a bridge sits between the intended residues, or whether a side chain is attached at the intended position.
MS/MS breaks the molecule into fragments and can support the sequence and the location of modifications, but only where the fragments actually cover the region in question. NMR can show the chemical environment of atoms and, with 2D experiments, how they connect. For a peptide of this size it needs assignment and interpretation by a specialist. A raw spectrum with no assignment is a picture, not an identity result.
The next page covers what the published structure says and what it does not.
Batch matching and chain of custody
A report describes the sample the laboratory received. To say it describes your vial, you need to connect them.
- The sample name, batch or lot number and date on the report match what is on the vial or kit.
- The report states who submitted the sample and how it was drawn from the batch.
- The test date makes sense against the production and shipping dates.
- A later batch is not assumed to match an earlier test.
- A pooled or preliminary sample is not treated as the final production batch.
Without those links, a report is evidence about a sample, not about your product.
How to check that a report is genuine
- Find the issuing laboratory’s own verification route and type its address yourself. Do not rely only on a link or QR code supplied alongside the product.
- Check that the report on the laboratory’s site matches the one you were shown, field by field: sample name, batch, date, results and units.
- Be cautious with cropped images. A crop that removes the laboratory name, task number, date or verification route cannot be verified.
- Read the units and the method. Milligrams of what, measured against which standard?
- Look for what the report does not contain. Many reports include only purity and quantity. If structure, endotoxin or sterility results are absent, they were not tested or not shown.
- Ask for the raw chromatogram or spectrum if a claim depends on it.
What we reviewed
In the project’s editorial review of public community material, we looked for reports that could be checked against their source.
- Three original laboratory-hosted reports were recovered. All three showed detectable Eloralintide, HPLC purity between about 99.3% and 99.8%, and measured amounts between about 10% and 38% above the nominal label. None displayed a structural or endotoxin result.
- One reproduced image of a report, circulated in a social media post, listed a nominal 5 mg sample with measured amounts around one tenth of that, alongside purity near 99.6%. The crop lacked the laboratory name, task number, test date and verification route, so its original has not been authenticated. We treat it as a lead and nothing more.
- Posts that attached documents often showed things that are not analytical evidence, such as a pH strip photograph and a medication-level tracker screenshot.
Four documents cannot give a failure rate, and we do not estimate one. The three original reports also do not show that every vial in the market contains the stated amount, and they do not show structure. Both the above-label results and the single below-label lead are limited in the same way: they describe specific samples, with traceability gaps.
This was not a complete archive of any community. Some forums required a login, and part of one long discussion was restricted.
What does not authenticate a sample
- Feeling an effect, or feeling nothing. Both depend on dose, individual response and other medicines, and trials use placebo for this reason.
- How a powder dissolves. Solubility depends on the solvent, the pH, the salt form and handling.
- pH strips, tracking apps and photographs of vials.
- A purity figure with no identity or quantity data.
- An image called an NMR result that is not an assigned spectrum. One image presented this way in the material we reviewed was not a spectrum at all.
A practical standard for verifying authentic Eloralintide
There is no single test that proves a vial is real Eloralintide. What you can do is ask how much of the following a set of documents actually covers. The more rows that are filled with checkable data, the stronger the case that material is authentic.
| Standard | What strong documentation looks like | Weak signals |
|---|---|---|
| Verifiable report | Issued by an identifiable laboratory, with a task number, a date and a verification route you can open yourself | Cropped images, no laboratory name, links that only the seller supplies |
| Identity by accurate mass | Observed and expected mass shown with the calculation and the error stated | “Mass confirmed” with no numbers |
| Structural evidence | MS/MS fragments covering the modification sites, or assigned 2D NMR consistent with the bridge | An unassigned spectrum, or a picture described as NMR |
| Quantity | A calibrated assay with the reference standard and the unit (peptide content or powder mass) stated | A milligram figure with no method |
| Purity | HPLC purity with the method named | Purity used as a stand-in for identity or amount |
| Batch link | Batch and sample details on the report match the vial; the test is of the batch you hold | A preliminary or pooled test offered for a later batch |
| Contamination | Endotoxin and sterility results with units, limits and method | A bare “pass” |
These are the same questions you would use to separate a genuine Eloralintide result from a fake Eloralintide claim. A seller that publishes documentation meeting several rows is easier to check than one that publishes a purity number alone, but a report still only describes the sample the laboratory tested. It does not guarantee any other vial.
Looking at sources for research use only? Read where to buy eloralintide (research use only) and what to check first before you compare any seller. If you are unsure about the rules, start with is it legal to buy eloralintide.
Research-use supplier
Where to get eloralintide for research: the source that met our standard
After reviewing the Eloralintide testing landscape, including public laboratory reports, community testing discussions and available commercial documentation, one source stood out.
One supplier was the only commercial vendor we identified whose publicly available analytical documentation met the verification standard we were looking for and gave us confidence that the tested material was authentically Eloralintide.
Their signed laboratory reports for one batch state that a methylene thioacetal bridge is present and that NMR with HSQC and COSY supports the expected bridge. That does not mean other sources are counterfeit. It means we could not verify them to the same standard.
VIEW ELORALINTIDE & ANALYTICAL DOCUMENTATION →
This link goes to a website that sells research use only compounds to qualified researchers for laboratory research use only, not for human consumption. A report applies to the batch tested and does not guarantee any other vial. Not equivalent to Eli Lilly clinical-trial material. Not medical advice.
- Signed laboratory reports for one batch state that a methylene thioacetal bridge is present (LC-HRMS/MS) and that NMR with HSQC and COSY supports the expected bridge.
- These are the laboratory’s signed summary conclusions. They do not give an observed mass, a ppm error, fragment-by-fragment sequence coverage or a peak-assignment table.
Frequently asked questions
What does COA mean?
Certificate of analysis. It is a report from a laboratory, or from a manufacturer, listing test results for a specific sample. It is not a regulatory approval.
Does 99% purity mean a vial is 99% Eloralintide?
No. HPLC purity is the share of detector signal in the main peak under one method. It says nothing on its own about the amount of peptide, or about whether the main peak is the intended molecule.
Can LC-MS confirm Eloralintide?
It can confirm that the mass fits, which is a useful screen. Confirming the arrangement of the bridge and the side chain needs fragmentation data or NMR that actually covers those regions.
Why can a measured amount be higher or lower than the label?
Possible reasons include how the vial was filled, the reference standard and calibration, and whether the result is peptide content or powder mass. A single report seldom shows which applies.
Does a passed endotoxin or sterility test show the peptide is genuine?
No. Those tests address contamination. They do not address identity, purity or amount.
How do I verify a COA?
Use the issuing laboratory’s own verification route, compare every field with the sample’s batch details, and treat cropped or incomplete images as unverified.
How can I tell whether Eloralintide is real or fake?
No single test settles it. Look for a verifiable laboratory report tied to the batch, an accurate-mass match, fragmentation or assigned NMR that covers the modified regions, and a separate quantity result. Documents that are cropped, cannot be verified, or give only a purity percentage leave the question open. Open is not the same as fake.
What does a failed or questionable Eloralintide test mean?
It depends on what failed. A low measured amount, an unexpected mass and a contamination result are different findings with different possible causes, including sampling, method and calibration. One questionable report describes one sample and does not by itself show a pattern.
References
- Briere DA, et al. Eloralintide (LY3841136), a novel amylin receptor agonist for the treatment of obesity: from discovery to clinical proof of concept. Molecular Metabolism. 2025;102:102271. DOI 10.1016/j.molmet.2025.102271. PMID 41109426.
- ICH Q2(R2). Validation of analytical procedures. International Council for Harmonisation. [method-validation background]
- ICH Q6B. Specifications: test procedures and acceptance criteria for biotechnological and biological products. [background on identity, purity and content as separate attributes]
- United States Pharmacopeia general chapters on bacterial endotoxins and sterility tests. [background on those assays]
Eloralintide is investigational and not approved. This page is educational information and not medical advice. .