This page describes how material sold here is tested, what those tests establish, and — just as importantly — what they do not. The coverage figure below is generated from the catalogue itself rather than written by hand, so it reflects the position today.
24 of 67 catalogue items currently have a published certificate of analysis. Some batch data shown on this site is sample data added for design purposes. See the full list
What is tested
Two questions, answered by two instruments.
- Identity — mass spectrometry. The measured molecular mass is compared with the mass calculated from the sequence. Agreement is evidence that the material is what the label says.
- Purity — high-performance liquid chromatography. The sample is separated into its components and the target is expressed as a percentage of total detected peak area.
Both have limits worth understanding before relying on them. Mass spectrometry confirms mass, not sequence order. An HPLC purity percentage is relative to detected material, so it is not the same as peptide content by mass — salts and residual water are typically not represented. We set this out in detail in how to read a certificate of analysis, including the red flags that make a report worthless.
Testing is per lot, not per compound
Synthesis is a batch process. Two runs of the same sequence, by the same manufacturer, produce material with different impurity profiles. A report therefore describes one lot and says nothing about any other.
This is the single most common way testing claims mislead. A supplier can hold a genuine, well-conducted report and still be telling you nothing about the vial you received, because the report covers a different lot. Every certificate we publish carries the lot number it applies to, and that number is printed on the product page beside it. If the two do not match, the report is not evidence about your material.
Who does the testing
We commission testing from laboratories that publish their own reports, at a verification address on the laboratory’s own domain. That distinction matters more than it looks: a report hosted here is our assertion about our material, while a report on the laboratory’s servers is something you can check without trusting us.
Where a report is hosted on our own site rather than a laboratory verification domain, the product page says so explicitly instead of presenting the two as equivalent.
Two kinds of document that we do not treat as evidence about what we ship: a manufacturer’s certificate for the manufacturer’s batch, which describes material before it was repackaged; and a report obtained by anyone else for a different lot.
When a lot does not pass
A lot that fails identity or falls short on purity is not listed. The commercial pressure runs the other way — testing is a cost, and a failed lot is a written-off purchase — which is precisely why the decision has to be made against a stated threshold rather than case by case.
Where a lot has sold out, its certificate stays published. Anyone who bought from that lot may still need the documentation, and removing it would break the link between a purchase and its evidence.
What testing does not establish
Identity and purity testing is a narrow instrument, and it is worth being explicit about what falls outside it. Material supplied here is not manufactured under a pharmaceutical quality system, and the following are not established by the reports we publish:
- Sterility. Material is not supplied sterile and is not tested for sterility.
- Endotoxin content. Not measured.
- Residual solvents and heavy metals. Not covered by identity and purity testing.
- Stability over time. A report is a snapshot at the date of analysis. It does not carry an expiry date or predict behaviour in storage — see storage and stability.
- Anything about biological activity. Testing establishes what a molecule is, not what it does.
These absences are what distinguish research-grade material from a medicine. They are not gaps we intend to close by wording; see what “research use only” means.
Checking a batch yourself
- Find the lot number on the vial.
- Open the certificates page and locate that lot.
- Follow the report link. Confirm it resolves to the laboratory’s own domain, not ours.
- Check that the lot number on the report matches the vial in your hand, and that the date of analysis is present.
If a lot number on a vial does not appear on that page, or the report does not match, tell us and we will resolve it or withdraw the listing.