Quality center
What we test, why it matters, and what it cannot tell you
Two numbers on a certificate answer two different questions. Purity asks how much of this is one thing. Identity asks whether that thing is what the label says. A supplier who shows you only one of them is showing you half the story.
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- 132
- Certificates published
- 27
- Compounds tested
- 3
- Assays covered
5 tests
Each one answers a question the others cannot
Reverse phase HPLC
The sample is pushed through a C18 column and the detector records what comes off and when. Purity is the area of the main peak divided by the total area of every peak. It tells you how much of the material is the one compound, and it cannot tell you which compound that is.
Mass spectrometry
The molecule is ionized and weighed. If the observed mass matches the theoretical mass of the intended sequence, the identity is confirmed. This is the test that catches a mislabeled or substituted compound, which purity alone will happily call 99 percent pure.
Net peptide content
A lyophilized vial holds counterions, residual water and salts alongside the peptide, so the label weight is not the peptide weight. Where the laboratory reports net peptide content, it is printed on the product page beside the purity figure.
Endotoxin screening
Bacterial endotoxin units per milligram, measured on the finished lot. Relevant to any cell culture work, where endotoxin can confound a result long before it reaches a toxic threshold.
Sterility
A compendial sterility test, USP <71> or USP <1223>, run on the finished lot. Not every laboratory in the corpus runs it, so the report for a given lot names whether it was performed.
Manufacture to vial
Where a batch comes from
Four steps, and the middle two are the reason a certificate on this site means anything: the laboratory is not ours, and its report is published as written.
- 01
Manufacture
Compounds are manufactured in American laboratories. The analytical laboratories that test them are independent of Response BioLabs, which neither owns nor controls them.
- 02
Independent testing
A sample from the finished lot goes to a third party analytical laboratory. Four appear across the current certificates, and the panel each one runs differs, so the report for a lot is the only statement of what was tested.
- 03
Publication
The report is published exactly as the laboratory issued it, as the original document rather than a retyped table, whether the number is 99.9 or 98.0.
- 04
Fill and ship
Vials are filled, capped and labeled. Where the laboratory prints a batch code, it matches the label; some laboratories identify a sample by their own submission number instead.
What a certificate cannot tell you
The limits, stated plainly
A certificate of analysis describes a sample taken from a lot at a moment in time. It is strong evidence about that lot and weak evidence about anything else, and there are four things it cannot do no matter how good the numbers look.
- It cannot tell you the vial in your hand was stored correctly after it left our cold room. Chain of custody ends where shipping begins.
- It cannot tell you the compound is safe or effective in any organism. Purity is a chemistry measurement, not a safety finding.
- It cannot tell you what the remaining fraction is. A 99 percent result means one percent is something else, and unless the certificate identifies it, nobody knows what.
- It cannot verify itself. A PDF is trivially editable. The value comes from the lab that issued it and the batch code that ties it to a physical lot.
We publish every result, including the ones we would rather round up, because a supplier who only shows you the 99.8 percent lots is telling you something about their record keeping, not their chemistry.
For research use only. Not for human consumption. Not FDA approved.