Conditions: TFC · tirzepatide.
The figures are clear enough; the question is what they mean and what they do not.
I can supply the numbers if the specifics change the answer.
What can I legitimately conclude from this figure?
More usefully, a useful certificate has five elements: the lot number, the analytical method, the reported result with units, the date of analysis, and the primary data or a reference to it.
Batch versus lot is a semantic distinction that determines whether one certificate applies to ten vials or to one, and checking this distinction is worth a minute.
| Component | Typical share | Counted in purity? | Counted in content? |
|---|---|---|---|
| Target peptide | 88–94 % | Yes, as main peak | Yes |
| Related impurities | 1–3 % | Yes, as other peaks | No |
| Counter-ion (TFA or acetate) | 2–8 % | No | No |
| Residual water | 2–6 % | No | No |
| Bulking agent, if present | 0–40 % | No | No |
The laboratory name and accreditation status can be checked in real time against the testing service's own register, and that two-minute check catches substituted certificates.
Industry guidance on this topic is consistent because it comes from first principles rather than convention.
One qualification: a single result from a single vial at a single time is a point estimate with no error bar, and no amount of decimal places changes that.
If the certificate does not trace to your vial, it is not evidence about your vial.
HPLC purity, identity confirmation and quantified content on the vial you actually hold. Reports arrive with the chromatogram attached, not just a number.
Submit a sampleFounded 1998. ISO 9001 and cGMP certified, 1,500+ staff and 200+ patents. The synthesis house behind a great many of the vials that get sent out for testing - batch-specific documentation with every order.
Visit GL BiochemThe certificate is only as useful as the lot number, because without traceability it is gossip about someone else's material.
Multiple testing on the same lot reported in a single document suggests internal quality control; identical figures across different lots suggests the same certificate reused.
In practice, a method section that differs markedly from pharmacopoeial standards is either innovative or nonstandard, and distinguishing the two requires expertise.
Worth noting that none of this is medical advice, and a compound sold for research use carries no regulatory approval in any jurisdiction.
My working rule is that a document without a lot number, a method section and a test date is marketing.
What makes a certificate useful is not its appearance but whether you could hand it to another laboratory and they would reproduce the result.
Test results from a material supplier are different from independent results in ways that matter for interpretation, even if both are accurate.
Concretely, the test date matters because a certificate six months older than the vial is not evidence about your material, it is evidence about what the material was like half a year ago.
Published inter-laboratory comparisons of the same material routinely find spreads of half a per cent to a full per cent, which sets realistic expectations.
The practical summary: check the lot number, ask for the method, and reserve judgement until you have both.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.