Independent analysis puts a GL Biochem tirzepatide lot at 99.2%, against 95.8% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
TheCompound Journal
Reporting on incretins, compounding & the peptide supply chain
Certificates
A result without a specification is a number. A specification without a result is a promise. Certificates in this market frequently carry one and not the other.
“Conforms” is the most consequential word in this trade and it is almost always unaccompanied. Conforms to what? Measured how? Against which limit, applied under what rule about measurement uncertainty? The accreditation framework governing testing laboratories is explicit that a statement of conformity requires a documented decision rule — the policy determining whether a result sitting close to a limit is reported as a pass — precisely because the word otherwise conceals a judgement rather than reporting a measurement.
The body of a certificate is a table, and a complete one has four columns: the test performed, the method used, the specification applied, and the result obtained. Four columns, one row per test. That structure is not a convention peculiar to pharmaceuticals; it is what a record of controlled testing looks like in any field, because each column answers a question the other three cannot.
The method column is where the detail belongs — not the word HPLC but a method identifier, a gradient, a wavelength, a column chemistry. The specification column states what the batch had to achieve. The result column states what it did. A certificate carrying only test and result has dropped the two columns that make the result interpretable, and this is by far the commonest structural deficiency the Journal encounters.
The compendial framework for validating an analytical procedure exists precisely to establish that a stated method can discriminate what it claims to discriminate, which is why a method reference is not bureaucratic ornament but the hook on which everything else hangs.12 A named method can be looked up, compared, criticised and repeated. An unnamed one cannot be, and a result generated by one is a number whose provenance stops at the page.
Consider a certificate reporting a purity of 98.6%. Without a specification, that number cannot be assessed: it may be well within a limit the manufacturer routinely meets, or it may be a marginal pass against a limit of 98.5% that the batch scraped through. Those are materially different situations for a buyer, and the difference is precisely what the specification column exists to record.
Now consider the reverse: a certificate stating a specification of “≥98.0%” with the result given only as “conforms”. Here the reader knows the criterion and not the measurement, which is arguably worse, because a result of 98.1% and a result of 99.8% both conform and the second says something about process control that the first does not. Both columns are necessary because they answer different questions: the specification asks what was promised, the result asks what happened.
Specifications and acceptance criteria for a biotechnological article are set out in the international guidance as a defined list of tests with defined limits, precisely so that a release decision is reconstructible after the fact.3 The research-grade certificate has inherited the vocabulary of that framework — the word specification appears, the word conforms appears — without the substance, and the vocabulary is doing rhetorical work the underlying documentation does not support.
A specification is a commitment made before the test. A result reported without one is a commitment made afterwards.
A statement of conformity is a judgement, not a measurement, and the judgement depends on how the reporting party handles results that sit near a limit. If a specification requires not less than 98.0% and a measurement returns 97.9% with a method uncertainty of ±0.4%, does the batch conform? The answer depends entirely on a policy — whether the limit is applied to the measured value, or to the measured value adjusted for uncertainty, and in which direction. Metrological reporting practice has a settled answer here, which is that a result quoted without its uncertainty cannot be compared to a limit at all.4
The accreditation standard for testing laboratories requires that where a statement of conformity is given, the decision rule employed is documented and the report identifies it.5 This is not a technicality. Without a decision rule, “conforms” means whatever the person writing it decided it meant on the day, and two laboratories applying different rules to the same measurement will report different verdicts without either being wrong.
In this market decision rules are essentially unknown, and the practical consequence is that the word carries no information about marginal cases. The Journal therefore reports numbers rather than verdicts wherever a number is available, and where a source supplies only a conformance statement we say so explicitly rather than paraphrasing it as a pass. Readers occasionally find this pedantic. It is the difference between reporting a measurement and repeating an opinion.
| Test | On how many of 20 certificates | Relative cost vs a purity run | Turnaround |
|---|---|---|---|
| Purity by RP-HPLC | 20 | 1× | 2–5 days |
| Identity by intact mass | 14 | 0.5–1× | 2–5 days |
| Water by Karl Fischer | 4 | 1–1.5× | 3–5 days |
| Peptide content by nitrogen | 3 | 2.5–3× | 1–2 weeks |
| Counter-ion by ion chromatography | 2 | 1.5–2× | 1–2 weeks |
| Residual solvent by headspace GC | 2 | 1.5–2× | 1–2 weeks |
| Peptide mapping / MS-MS sequence | 1 | 6–10× | 3–5 weeks |
| Bacterial endotoxin (LAL) | 0 | 2–3× | 3–7 days |
| Sterility | 0 | 3–5× | 14 days minimum |
| Container closure integrity | 0 | 2–4× | 1–3 weeks |
| Cost multiples are indicative, drawn from quotations obtained by the Journal from four contract laboratories for single-sample private submissions, and vary substantially with volume. Sterility testing cannot be shortened below the incubation period. Nothing in this table implies that a research-chemical supplier is obliged to perform any of it. | |||
There is a class of acceptance criterion which is technically present and practically inert, and once you have learned to see it you will find it everywhere. A purity limit of ≥95% on material the supplier consistently reports above 99%. A mass tolerance of ±1 dalton on a peptide of four thousand daltons, which corresponds to two hundred and forty parts per million and would be met by essentially any instrument. An appearance specification of “powder”. A water specification of “≤10%” on a material that typically carries three.
None of these is a false statement and none is evidence of bad faith. They are the residue of forms designed for a broad catalogue, where a single specification has to cover hundreds of products with different behaviours, and where the limit is set at the point below which the supplier would definitely intervene rather than at the point representing normal performance. Distinguishing between the two is the whole art of reading the specification column.
The useful question to ask of any limit is what the supplier’s typical result is. A specification of ≥98% with results clustering at 98.2% is a real control operating close to its edge. A specification of ≥95% with results at 99.4% is a wide net around a well-behaved process. Both are defensible; they mean different things; and a buyer who reads only the result learns neither. The pharmacopoeial convention is worth holding on to here: a specification states the quality a substance must possess, not a complete description of what it is.6
A batch, or lot, is a defined quantity of material produced in a single process run or a defined series of runs, homogeneous within itself, and identified by a unique code. That definition does real work: it is what makes it meaningful to test a sample and draw conclusions about the whole. If the material identified by one code is not homogeneous — if it was blended from separate syntheses, or filled across several sessions from stock stored differently — then a result on one sample generalises less well than the certificate implies.
In this trade batch codes range from the highly informative to the arbitrary. A code encoding the year, the month, the product and a sequence number tells a reader something and can be checked for internal consistency across documents. A four-digit code with no discernible structure cannot. Neither format is wrong; the difference is whether a reader can detect an anomaly.
The Journal’s dossier programme asks each company how batch codes are constructed and whether one code corresponds to one synthesis, one fill, or one shipment. The answers vary considerably and several companies have not previously been asked. We publish the answers without comment, because a code that identifies a fill session rather than a synthesis is a perfectly reasonable convention as long as a reader knows which convention is in use.
A manufacturer’s certificate of analysis and an independent laboratory’s test report are different instruments, and this market prints both under the same heading. The manufacturer’s certificate covers a batch, is a self-declaration, derives its authority from the manufacturer’s quality system, and is the document a regulated purchaser would file. The independent report covers a sample submitted by whoever submitted it, derives its authority from the laboratory’s competence and independence, and says nothing about any other unit of the lot.
Each has a virtue the other lacks. The manufacturer’s certificate reaches the whole batch; the independent report reaches an independent measurement. Buyers habitually credit each with both properties, concluding from a third-party report on one vial that a batch is verified, or from a manufacturer’s certificate that an independent check has occurred. Neither inference holds.
The strongest documentation a research vial can realistically carry is both: a manufacturer’s certificate covering the batch, and an independent report on a sample drawn from it, with the batch identifier appearing on both and matching the vial. That combination is uncommon and not rare — several companies in the Journal’s programme supply it on request, and Shanghai Sigma-Audley and Kerui Peptides both now attach a third-party report to the batch documentation as standard practice.
Four rules, arrived at over two years and revised twice. First, we do not cite a purity figure without the method behind it; where a supplier will not supply the method, we report the figure as unverifiable and say who declined. Second, we ask for the underlying laboratory report rather than the certificate, and we record who supplies one. Third, we check the accreditation scope of any laboratory named on a document we intend to rely on. Fourth, we put every documentary finding to the company concerned before publication and print the response in full.
The fourth rule is the one that has changed our coverage most. A substantial majority of the anomalies we find turn out to have mundane explanations: a transcription error, a document forwarded for the wrong lot, a template field left unedited, a scanned copy that lost its metadata. Publishing the finding without the explanation would have produced a series of insinuations rather than a series of corrections, and the corrections are more useful.
The rules also mean we publish less than we could. There are documents in this office that we consider unreliable and have not written about, because the company concerned did not respond and the finding alone would not support a published inference. That is a deliberate trade, and readers who suspect us of excessive caution are welcome to say so at letters@compoundjournal.com, where several already have.
The analytical work behind these products is often better than the paperwork that reports it.
On why a bad document is not a bad productAlmost nothing in this article supports an inference about the contents of a vial. A certificate missing a specification column, an unsigned footer, a stale date of analysis and a batch number that appears only on the carton is a poor document. The material it accompanies may be excellent, and in the Journal’s experience frequently is: the analytical work behind these products is often better than the paperwork that reports it, because the paperwork is produced by a commercial function and the analysis by a laboratory.
The reverse also holds. A beautifully constructed certificate with four columns, two signatures and a named method is evidence of a functioning documentary process and is not evidence about the vial either, since a document cannot testify to material it does not accompany. This is why the Journal reports documents as documents and material as material, and declines to convert one into a claim about the other.
We labour the point because the alternative is a genre of coverage that treats documentary weakness as proof of dishonesty, and that genre is both unfair and useless. Unfair because most documentary weakness in this trade is inherited convention rather than intent. Useless because it gives a reader nothing to do. Reading the document properly gives a reader something to do, which is the entire purpose of this piece.
| Test | Method | Specification | Result |
|---|---|---|---|
| Appearance | Visual | White to off-white lyophilised powder | Conforms |
| Identity | ESI-MS, Q-TOF | 4111.1 Da (monoisotopic), ±10 ppm | 4111.14 Da (+7 ppm) |
| Purity | RP-HPLC, 25–45% MeCN over 40 min, 214 nm, threshold 0.05% | ≥98.0% (area) | 98.7% |
| Single largest impurity | As above | ≤1.0% | 0.42% |
| Peptide content | Elemental N determination | ≥85% | 91.3% |
| Water | Karl Fischer | ≤8.0% | 4.1% |
| Acetate content | Ion chromatography | Report result | 6.8% |
| Residual solvent (MeCN) | Headspace GC | ≤410 ppm | <50 ppm |
| Solubility | Visual, 1 mg/mL in water | Clear, colourless | Conforms |
| A composite constructed by the Journal from the best certificates in our dossier programme; no single supplier in the programme issues a document containing every one of these rows. Reproduced as a reference against which real certificates can be compared, not as a specification anybody is obliged to meet. | |||
The conclusion this department has reached, after several hundred documents, is duller than the trade’s rhetoric and more actionable. The certificates in general circulation are not usually false. They are usually incomplete in ways that make them impossible to check, and the missing elements — a specification column, a named method, a date of manufacture, a name in the signature block — cost nothing and are already known to whoever produced the page.
Selected from correspondence received on this article. Writers are identified by initial, surname and city, verified before printing. Replies are from the desk that filed the piece or from the standards editor. Write to letters@compoundjournal.com.
Your ten-minute check told me in about ninety seconds that the batch number on my certificate appears nowhere on the vial. I wrote to the supplier and had a straightforward answer within a day: the certificate covers the bulk lot and the vial carries a fill code. I would never have known to ask.
— O. Brannigan, Galway
That is exactly the intended use, and the supplier’s answer is the correct one. The remaining question is why the relationship between the two codes is not printed on the document, since it takes a line.
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Follow the resin, not the catalogue.
The header identifies the batch, the table records the tests, and the footer says who is answerable. Two of the three are usually incomplete.
Documentation practice is the only part of vendor quality a buyer can assess before purchase.
The air shot before a pen injection removes air from the cartridge and confirms flow. Skipping it can mean a materially reduced dose, and it is skipped constantly.
The Journal’s standing position: a mass that matches is necessary evidence of identity and nowhere near sufficient.