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What Should You Check Before Choosing a Research Peptide Supplier? COAs, HPLC & Batch Traceability
I've been looking at how people compare research peptide suppliers, and a lot of comparisons seem to stop at two things:
price and “99% purity.”
Neither tells you very much on its own.
If you're evaluating a research peptide supplier for laboratory procurement, what do you actually check before ordering?
These are the areas I think matter most.
A Certificate of Analysis is much more useful when you can connect it to the material currently being supplied.
Ideally you should be able to identify:
compound batch or lot number testing date analytical laboratory report/reference number analytical methods used
A generic PDF showing “99% purity” without a batch reference doesn't establish that the material currently being sold is the material that was tested.
This seems to be one of the most misunderstood parts of peptide testing.
HPLC can provide information about chromatographic purity, but a large HPLC peak does not by itself prove molecular identity.
Mass spectrometry provides a different piece of the analytical picture by comparing the observed molecular mass with the expected compound.
When reviewing a supplier, I'd rather see both parts of the evidence than a purity percentage presented without context.
There is an obvious difference between:
“We tested our own product and say it is 99% pure”
and:
“An independent analytical laboratory tested this specific batch and here is the report.”
Neither removes the need to read the actual report, but independent testing creates a much clearer evidence trail.
Historical testing is interesting because it shows whether the supplier is repeatedly testing incoming production rather than relying indefinitely on one favourable certificate.
New-U's published Certificate of Analysis library is one example of this approach. Current and archived reports can be compared rather than having the previous analytical record disappear when inventory changes.
The useful traceability chain should look something like:
Compound → vial → batch/lot → COA → analytical result
If those identifiers don't connect, the COA becomes much less useful.
Testing isn't the entire procurement process.
I'd also look at:
storage information packaging fulfilment records tracking batch identification availability of documentation before purchasing clearly stated Research Use Only status
New-U has a broader guide to buying research peptides online covering sourcing, batch testing, COAs and procurement considerations.
The question
What is the first thing you check when evaluating a research peptide supplier?
Is it the independent laboratory, the chromatogram, mass-spec identity, batch matching, testing date, historical COAs, or something else?
And what would make you reject a supplier immediately?
Interested to hear how other researchers approach supplier due diligence.
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Research peptides at >99% HPLC-verified purity, third-party tested by Janoshik Analytical & Freedom Diagnostics, with Certificates of Analysis published per released batch. Supplied strictly for laboratory research use.
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