Wrong Molecule in the Vial: What 2026 Identity Tests Found, and Why Purity and Content Mean Nothing Without Identity
Identity, content and purity are three separate lab tests, and a failed identity leaves the other two indeterminate. This article sets out what 2024 to 2026 analyses of peptide vials found.
"How do you know if your Reta is Fake?" asks a thread title in r/PeptidePathways from 19 July 2026, a thread that drew 90 comments. A forum reply cannot settle that; a laboratory can settle part of it. It can say whether the labeled molecule is present, how much of it there is against a reference standard, and which other peptide-like substances appear next to it in a chromatogram. It cannot, from those answers alone, say everything else a vial contains. The one-in-three failure figure covers aggregate failure rates, and our article on HPLC and mass spectrometry covers both methods and content. This article is about identity, the test that decides whether the other numbers mean anything. It is informational only, with no testing, dosing or purchasing advice.
TL;DR: identity decides whether the other numbers mean anything
- Identity, content and purity are three separate questions with separate methods. The EU guideline on synthetic peptides (EMA/CHMP/CVMP/QWP/367182/2025, in force since 1 June 2026) recommends at least two orthogonal methods for identity alone.
- A failed identity leaves purity and quantity indeterminate. A laboratory reported exactly that in a press release from a peptide vendor-directory site (not peer-reviewed; it says its results "do not prove that the vials were empty"), and Finnrick, a testing platform that does not run its own laboratory and sends samples to third-party labs, fails the whole sample.
- Wrong-molecule findings are on record: insulin in a vial sold as semaglutide (a peer-reviewed 2026 case report), four vials without their labeled active ingredients (WIRED report, 15 September 2026, read via the bioethics.com excerpt), and one of 18 samples sold as retatrutide with none of the peptide (as reported by ABC News, 28 August 2026).
- Right molecule, wrong amount is a separate failure: content 28.56 to 38.69 percent above label in a 2024 peer-reviewed semaglutide study, whose 7.7 to 14.37 percent figure is a share of powder mass, not purity.
- A label-claim test answers one narrow question, whether the claimed compound is there. It does not say what else is in the vial.
Research use only
Retatrutide and BPC-157 are sold here as laboratory research materials, not as medicines, and not for administration to a person or animal. Semaglutide, tirzepatide, insulin and the other substances named below appear only as subjects of published analyses. This article describes what tests measure and what those analyses reported; it makes no claim about any product, including ours, and contains no testing, dosing, reconstitution or purchasing instructions.
Retatrutide (LY3437943) is a synthetic 39-amino-acid peptide that acts on three receptors at once: GLP-1, GIP and glucagon. Supplied as a lyophilized powder for in-vitro research, with a batch-specific third-party certificate of analysis.
BPC-157 is a synthetic 15-amino-acid gastric pentadecapeptide, studied in rodent and cell-culture models for angiogenesis, cell migration and nitric-oxide pathway activity. Lyophilized powder, specified purity at or above 98% (HPLC), batch CoA.
GIP/GLP-1/glucagon agonists and metabolic pathways
Three questions, three methods, one order
Identity asks what is in the vial, content how much of the labeled substance, measured against a reference standard, and purity what else, as peptide-related impurities in a chromatogram. The EU guideline lists "identification", "purity" and "assay/content" as separate specification items, next to counter-ion content, water content, residual solvents and "bacterial endotoxins".
Identity means that the material matches the substance on the label. Methods include the molecular mass by mass spectrometry (MS, LC-MS), tandem mass spectrometry (MS/MS) for the sequence, retention time against a reference standard, amino acid analysis (AAA) and NMR. The EU guideline: "For the identification of the peptide as part of the specification and release, use of at least two orthogonal methods is recommended." A peer-reviewed paper on reference standards for synthetic peptides (McCarthy and colleagues, Pharm Res 2023) assigns each question its method, condensed here:
- Method
- NMR
- What it settles
- Structural features
- Method
- LC-MS/MS
- What it settles
- Peptide mass and amino acid sequence
- Method
- HPLC
- What it settles
- Main peak compared with a standard
- Method
- Amino acid analysis (AAA)
- What it settles
- Isoleucine versus leucine
- Method
- Chiral analysis
- What it settles
- Presence of D-amino acids
- Method
- HPLC (chromatographic purity)
- What it settles
- Quantity of peptide impurities
- Method
- HPLC
- What it settles
- Quantity of the peptide itself
Content is a quantity, and a quantity needs a reference. The EU guideline: "A test for Assay (e.g., based on a chromatographic method usually the same as for purity) using a reference standard should be considered." McCarthy and colleagues describe mass balance, in which "all species other than the native peptide (e.g., impurities, counter ions) should be identified and measured." Their worked example is explicitly theoretical: "the theoretical example described in Table VII would have a purity of 0.93 mg of peptide (free base) per mg of material on the anhydrous basis."
Purity in the chromatographic sense is the main peak's share of the total peak area. Under the EU guideline, peptide-related impurities should be "reported above 0.1%, identified above 0.5% and qualified above 1.0%." A purity figure states no milligrams, and it assumes that the main peak is the labeled peptide.
The order. Identity comes first because the other two numbers refer to it. Finnrick, a testing platform that does not run its own laboratory and sends samples to third-party labs, scores it that way: "A failed identity result fails the sample." A press release from a peptide vendor-directory site, not peer-reviewed (Peptide Critic, 13 August 2026), describes four vials bought at a Brooklyn smoke shop, two labeled as retatrutide and two as NAD+ (not a peptide), tested by Analytical Formulations: "Because the labeled substances could not be positively identified, the laboratory reported purity and quantity as indeterminate for all four samples." Its own caveat: "These results do not prove that the vials were empty, and we are not claiming that they were". Without identity, a purity figure describes an unknown main peak and a milligram figure counts an unknown substance.
What a label-claim test checks, and what it cannot see
A routine test can answer a narrower question. In a WIRED report of 15 September 2026 (read via the bioethics.com excerpt), Marco Krause, chief executive of the laboratory that ran the tests, said: "What we offer is simply a label claim analysis. So you send us what you claim to think it is, and then we run it against a standard and verify whether or not it's the right compound". When identification fails, the claimed compound has not been positively identified by that analysis; the test is not built to name what is there instead.
Raphaël Mazoyer of Finnrick described the same limit in an interview (London, 18 September 2026, published 19 September 2026): "We are seeing new modes of failure that we weren't seeing before". The interview reports: "Mazoyer said the company had previously assumed that an identity failure might simply leave an inert excipient such as mannitol. He now considers that assumption unsafe." And: "Mazoyer said unfamiliar buffers and other unexpected material may not be detected adequately by the routine purity, identity and quantity package."
The reverse case comes from a 2024 peer-reviewed study (Ashraf and colleagues, J Med Internet Res) that bought semaglutide from online sellers without a prescription; three vials arrived and three pen orders never did. Identity was confirmed: "the chromatogram only displayed 1 signal for each delivered sample, indicating the exclusive presence of semaglutide ... This indicates that the samples do not contain peptide-like impurities." Yet semaglutide was only 7.7 to 14.37 percent of the powder mass, so 85.6 to 92.3 percent of the powder was not semaglutide, and the study did not identify it.
The counter-ion is one more separate quantity. A 2025 peer-reviewed paper on trifluoroacetate (TFA) in synthetic peptides (Erckes and colleagues) notes that "TFA- can introduce a weighting error due to differences in the molecular weights of its salt forms" and stresses "the importance of counterion quantification and specification in assays with synthetic peptides."
What a percentage is a percentage of
- Chromatographic purity: the main peak's share of the total peak area. A ratio, no milligrams.
- Content: milligrams of the labeled peptide against a reference standard, often relative to the label (28.56 percent above label, for example).
- Peptide share of powder mass: peptide divided by weighed powder, as in the 2024 semaglutide study (PMID 39509151: 3.86 mg in 50.1 mg, 7.7 percent). The remainder needs its own measurement; there it was not identified.
Wrong molecule: what 2024 to 2026 analyses found
The findings below concern identity; the last column states the source type.
- Labeled as
- Semaglutide
- What was found
- "Toxicological analysis showed that the vial contained insulin instead of semaglutide"
- Failure type
- Different molecule
- Source type
- Case report, peer-reviewed
- Labeled as
- Four vials, one of them BPC-157
- What was found
- Labeled ingredients absent; "the BPC-157, for example, had no BPC-157 within it"
- Failure type
- Labeled molecule absent
- Source type
- Press report
- Labeled as
- Retatrutide (2 vials), NAD+ (2 vials)
- What was found
- Identity not confirmed in all four; purity and quantity indeterminate; the release says this does not prove the vials were empty
- Failure type
- Identity not confirmed
- Source type
- Press release, not peer-reviewed
- Labeled as
- Retatrutide (18 samples)
- What was found
- One vial contained none of the peptide
- Failure type
- Labeled molecule absent
- Source type
- Press report
- Labeled as
- Peptide products ("the obestatin case")
- What was found
- One product was "in reality a totally different peptide"
- Failure type
- Different molecule
- Source type
- Peer-reviewed, historical precedent
The insulin row is the one where the substitute was identified: a peer-reviewed 2026 hospital case report in which toxicological analysis found insulin in a vial sold as semaglutide (Antonacci and colleagues, Eur J Hosp Pharm, PMID 41125326). WIRED's reading of its results: "The negative results suggested that the vials were either mislabeled or, if they had at one point contained the correct ingredients, had been corrupted beyond recognition." The Peptide Critic release reports for its retatrutide samples "an abnormally large extraneous peak that suggested 'extreme contamination'", while stating that its results "do not prove that the vials were empty".
In this record, wrong-molecule results are not confined to a single source type: the four 2026 rows come from a case report, two press reports and a press release, all published between 13 August and 15 September 2026. Nor are they a survey: the counts are small, from one case to 18 samples, and the vials are those that reached a hospital, a reporter or a laboratory, not a designed sample of a market. They show that the failure type occurs, not how often.
Right molecule, wrong amount
In the 2024 semaglutide study, identity was confirmed and the amount was high: "The quantity of semaglutide content in each sample also substantially exceeded the labeled amount, with excesses ranging from +28.56% to +38.69%". The originator reference product, Ozempic, measured +5.05 percent.
As reported by ABC News on 28 August 2026, Leeder Analytical said it had tested 18 samples sold as retatrutide this year, "with only one matching its label claim. About 30 per cent had higher concentrations and about 30 per cent had lower concentrations, while one vial contained none of the peptide." The report does not account for the remaining samples and does not state the tolerance for "matching". Grace Hamann of Leeder Analytical told ABC: "the fact that we've had almost equal amount to be over 100 per cent than under 100 per cent, surprises me".
A letter by University of Queensland researchers (Piatkowski and colleagues, Drug Alcohol Rev 2026; its figures are known to us only through the ABC report, as we could not access the full text) covered three commissioned vials. ABC reports that one of the three vials contained less than the label indicated and that "two had much higher concentrations." Tim Piatkowski told ABC that he had not expected content that far above the label; in the group's testing of other substances, he said, content below the label had been far more common than content above it.
Low content also appears in manufacturer-authored work: a 2024 peer-reviewed analysis by authors employed by Novo Nordisk, the semaglutide originator (Hach and colleagues, Pharm Res), found that "several commercialized follow-on oral semaglutide DPs had a markedly lower quantity of semaglutide than the label claim" (DP: drug product).
The 7.7 to 14.37 percent figure is not a purity result
The 2024 semaglutide study is often quoted as having found a "purity" of 7.7 to 14.37 percent against a claimed purity of at least 99 percent, and its Table 4 heads the column "Measured purity". The figures are semaglutide as a share of the total powder mass (PMID 39509151: 3.86 mg measured in 50.1 mg of powder is 7.7 percent), not a chromatographic purity. The same study confirmed identity, found one chromatographic signal per sample and concluded that the samples "do not contain peptide-like impurities". What the other 85.6 to 92.3 percent of the powder is was not identified. The authors' reading, "low-mass, weakly ionizing impurities", is a hypothesis: "further studies using additional analytical techniques are necessary to conclusively identify contaminants." Endotoxin is a separate measurement again.
Right molecule, extra molecules: impurities
Right identity and amount do not exclude other peptide-like molecules. The EU guideline also names the limit of a single method: "If one analytical method for detection and quantification of all the peptide-related impurities is not appropriate to separate all impurities, additional independent method(s) may be needed. When co-eluting impurities are observed as one peak the qualification threshold of 1.0% applies unless otherwise justified. ... Control of diastereomers may require the development of specific methods." Co-eluting here means impurities that appear together as one peak.
A mass match has two blind spots. Isoleucine and leucine have the same mass; amino acid analysis or MS/MS tells them apart, and McCarthy and colleagues note that amino acid analysis "is still a useful tool when discrimination between Leucine and Isoleucine is required." The D- and L-forms of an amino acid also share one mass. A 2023 peer-reviewed method paper (Strege and colleagues) states that "the undesirable d-isomers can be introduced as impurities in amino acid starting materials and can also be formed during peptide synthesis", and its chiral HPLC-ESI-MS/MS method recovered D-amino acid substitutions at each residue of an octapeptide "across the 0.1-1.0 % range of interest."
Impurities can also form when two ingredients of one product react. A 2026 peer-reviewed paper by authors employed by Eli Lilly, the tirzepatide originator (Jordan and colleagues, Expert Opin Drug Saf), reported "a widespread and previously unidentified impurity in compounded tirzepatide-B12 products resulting from a chemical reaction between tirzepatide and certain analogs of B12", which it describes as "present at substantial levels"; its "clinical effects ... are unknown".
For follow-on semaglutide, Hach and colleagues (authors employed by Novo Nordisk) found "new impurities and impurity patterns, including high molecular weight proteins, trace metals, anions, counterions, and residual solvents." A 2026 peer-reviewed paper, also by authors employed by Novo Nordisk (Kopp and colleagues, Pharm Res), reported that follow-on and compounded products "had distinct impurity profiles (amino acid deletions/additions and unidentified impurities) versus the originators."
Endotoxin is its own dimension, not part of a chromatographic purity; the EU guideline lists "bacterial endotoxins" separately. In the 2024 semaglutide study, one vial measured 8.9511 EU/mg and the other two were reported as less than 2.8658 EU/mg and less than 2.1645 EU/mg. A preprint, not peer-reviewed, by Mendias and Awan (abstract only) reports that "measurable endotoxin contamination was present in 15% of samples." Finnrick applies an endotoxin limit only in its Accuracy focus mode.
What aggregate pass and fail numbers can and cannot say
Finnrick's methodology page (data as of 20 September 2026) states that "Lab results are used to evaluate identity, purity, and fill accuracy". Its five scoring modes pair a purity cutoff with an allowed deviation in amount: Purity focus 99.5 percent and ±35 percent, Finnrick Standard 99.5 and ±25, Purity focus strict 99.8 and ±35, Super strict 99.8 and ±15, and Accuracy focus 98 percent and ±20 percent, the only mode with an endotoxin limit (40 EU per sample).
The retatrutide page lists 3,858 tests across 293 vendors since 17 December 2024, scored in Purity focus. The history shown covers the 200 most recent tests, 13 August to 20 September 2026: 142 pass, 54 fail, 4 incomplete, with no public breakdown by failure type. A fail there can stand for a failed identity, an amount outside the range or a purity below the cutoff. The Mazoyer interview adds "approximately 21,275 testing requests submitted between February 2025 and May 2026", with the caveat: "These figures describe requests submitted through Finnrick rather than completed tests".
The largest data set is the Mendias and Awan preprint, not peer-reviewed (24 April 2026, abstract only): "A total of 6441 peptide samples across fourteen compounds ... were analyzed. ... Between the two models, 41.6% to 71.1% of samples failed to meet basic quality criteria". Our article on the one-in-three failure figure discusses it in full. A pass rate folds all three failure types into one number unless the source splits them.
What the community asks
What the community reports
Demand, not evidence. In our Reddit corpus (212,225 posts, 1 August 2025 to 16 September 2026, posts only, no comments), 35 thread titles in the 12 months to 16 September 2026 contain "fake reta" or "fake retatrutide". In the same 12 months, Janoshik is named in 427 posts and Finnrick in 148 posts.
- Subreddit
- r/Retatrutide
- Date
- 26 June 2026
- Score
- 61
- Comments
- 62
- Subreddit
- r/Retatrutide
- Date
- 26 January 2026
- Score
- 24
- Comments
- 68
- Subreddit
- r/PeptidePathways
- Date
- 19 July 2026
- Score
- 8
- Comments
- 90
- Subreddit
- r/Peptidesource
- Date
- 15 June 2026
- Score
- 45
- Comments
- 6
- Subreddit
- r/PeptidePathways
- Date
- 10 July 2026
- Score
- 8
- Comments
- 65
"Stop posting photos of your cloudy vials" makes, as a title, the point our HPLC and mass spectrometry article makes analytically: how a vial looks is not an identity measurement.
Where each answer appears on a lab report
The steps below describe a document, not a procedure.
The identity line
Names the method, for example mass spectrometry, and what was observed: a measured mass or a match to a reference. Without this line, the first question stays open.
The content line
States a quantity in milligrams against the labeled amount and, where given, the reference standard it was measured against.
The purity line
States a percentage. What it means depends on what it is a percentage of: chromatographic peak area, or something else, such as powder mass.
Field-by-field reading is covered in how to read a certificate of analysis and how to read an HPLC chromatogram; what a report leaves out in what a CoA does not test; report verification in verifying a Janoshik CoA and how to spot a fake peptide CoA; commissioned vial testing in our lab-testing article.
Our own reports are on the CoA page; this article does not assess them.
Where these substances sit in our catalog
Retatrutide and BPC-157 are listed in our catalog as laboratory research materials.
Triple agonist, GLP-1-class research
FAQ
Sources
- Reddit corpus, our own extraction: 212,225 posts, 1 August 2025 to 16 September 2026, posts only, no comments; counts as stated in the article; threads cited by title, not linked.
- European Medicines Agency. Guideline on the development and manufacture of synthetic peptides, EMA/CHMP/CVMP/QWP/367182/2025, adopted by CHMP on 1 December 2025 and CVMP on 4 December 2025, in force from 1 June 2026. https://www.ema.europa.eu/en/documents/scientific-guideline/guideline-development-manufacture-synthetic-peptides_en.pdf
- Peptide Critic (press release via PR Newswire). Four Vials Bought at Brooklyn Smoke Shop Fail Identity Testing. 13 August 2026. Press release, not peer-reviewed. https://www.prnewswire.com/news-releases/four-vials-bought-at-brooklyn-smoke-shop-fail-identity-testing-302851353.html
- Finnrick. Methodology page and retatrutide page, read 23 September 2026 (data as of 20 September 2026). https://finnrick.com/methodology and https://finnrick.com/products/retatrutide
- Antonacci G, Bortignon E, et al. Hypoglycaemic coma induced by a falsified semaglutide product: a case report. Eur J Hosp Pharm. 2026;33(5):486-489. PMID 41125326. https://pubmed.ncbi.nlm.nih.gov/41125326/
- WIRED. Those Viral Bodega Peptides Aren't Actually Peptides. 15 September 2026, read via the bioethics.com excerpt. https://bioethics.com/archives/104105
- ABC News, report of 28 August 2026 on Leeder Analytical testing and the University of Queensland letter. https://www.abc.net.au/news/2026-08-28/black-market-peptides-dangerous-doses/107059092
- Ashraf AR, Mackey TK, et al. Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription: Market Surveillance, Content Analysis, and Product Purchase Evaluation Study. J Med Internet Res. 2024;26:e65440. PMID 39509151. https://pubmed.ncbi.nlm.nih.gov/39509151/
- McCarthy D, Han Y, et al. Reference Standards to Support Quality of Synthetic Peptide Therapeutics. Pharm Res. 2023;40:1317-1328. PMID 36949371. https://pubmed.ncbi.nlm.nih.gov/36949371/
- Interview with Raphaël Mazoyer (Finnrick), London, 18 September 2026, published 19 September 2026. https://krysia0430.substack.com/p/inside-finnrick-peptide-testing-paywalls
- Erckes V, Streuli A, et al. Towards a Consensus for the Analysis and Exchange of TFA as a Counterion in Synthetic Peptides and Its Influence on Membrane Permeation. Pharmaceuticals (Basel). 2025;18(8):1163. PMID 40872554. https://pubmed.ncbi.nlm.nih.gov/40872554/
- De Spiegeleer B, Vergote V, et al. Impurity profiling quality control testing of synthetic peptides using liquid chromatography-photodiode array-fluorescence and liquid chromatography-electrospray ionization-mass spectrometry: the obestatin case. Anal Biochem. 2008;376:229-234. PMID 18342612. https://pubmed.ncbi.nlm.nih.gov/18342612/
- Piatkowski T, Craven A, et al. Composition and Labelling Accuracy of Products Sold as Retatrutide in Australia. Drug Alcohol Rev. 2026;45(6):e70231. PMID 42559975. Full text not accessible to us; figures as reported by ABC News. https://pubmed.ncbi.nlm.nih.gov/42559975/
- Hach M, Engelund DK, et al. Impact of Manufacturing Process and Compounding on Properties and Quality of Follow-On GLP-1 Polypeptide Drugs. Pharm Res. 2024;41:1991-2014. PMID 39379664. Authors employed by Novo Nordisk. https://pubmed.ncbi.nlm.nih.gov/39379664/
- Strege MA, Oman TJ, et al. Enantiomeric purity analysis of synthetic peptide therapeutics by direct chiral high-performance liquid chromatography-electrospray ionization tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci. 2023;1219:123638. PMID 36857849. https://pubmed.ncbi.nlm.nih.gov/36857849/
- Jordan B, Arbogast L, et al. A novel, widespread impurity in mass-compounded tirzepatide/B12 products: potential patient safety implications. Expert Opin Drug Saf. 2026;25(5):837-845. PMID 42010938. Authors employed by Eli Lilly. https://pubmed.ncbi.nlm.nih.gov/42010938/
- Kopp KL, Lamberth K, et al. Impurities and Potential Immunogenicity Associated With Follow-on and Compounded Glucagon-like Peptide-1 Receptor Agonists. Pharm Res. 2026;43:2861-2886. PMID 42533250. Authors employed by Novo Nordisk. https://pubmed.ncbi.nlm.nih.gov/42533250/
- Mendias CL, Awan TM. Preprint, not peer-reviewed. Preprints.org 202604.1748 v1, 24 April 2026; abstract only. https://doi.org/10.20944/preprints202604.1748.v1
Research use only. Retatrutide and BPC-157 are sold here as laboratory research materials, not as medicines, and not for administration to a person or animal. Semaglutide, tirzepatide and insulin appear in this article only as subjects of published analyses; PeptidesDirect does not sell them. Nothing in this article is testing, dosing or purchasing advice, and nothing here characterizes any product, including ours.
Research context for English-speaking buyers
Most of our English-speaking customers ship to the UK, Ireland, Malta or other English-as-second-language EU territories. The regulatory picture differs per country.
- Relevant authorities
- MHRA (UK, post-Brexit), HPRA (Ireland, EU-aligned), FDA Section 503A bulks list (US, restricted Cat 2 status of several peptides as of 2026)
- Customs and VAT
- EU shipments include VAT, the rate depends on the destination country; UK shipments after Brexit are now extra-EU and may attract UK VAT plus a handling fee at import
- Typical shipping window
- EU 2-4 working days, UK 4-7 working days, other international 7-14 working days, depending on customs
Research-grade peptides shipped from our EU warehouse are sold for laboratory use only and are not authorised for human or veterinary therapeutic application in any of the destination jurisdictions. US customers should be aware that the FDA Section 503A bulks list classification (and the April 2026 reclassification of twelve compounds) only governs compounding pharmacies, not direct-to-researcher imports for non-clinical work. UK buyers should declare the consignment on import and may be asked for a research justification by HMRC. We provide a CoA per batch identified by colour code rather than serial number; customs sometimes asks for this document when clearing the parcel.