Certificates of analysis (COA)
A certificate of analysis is the lab report that proves what is actually in a vial. Here is how COA testing works, what each test confirms, and how every Peptide.ST batch is covered by both a first-party and an independent third-party certificate.
Every compound we ship is supplied strictly for laboratory research use only, not for human or veterinary use. A COA is the single most useful document for a researcher: it is how you confirm that the peptide in the vial matches the peptide on the label, and how pure it is, before you design anything around it.
What a certificate of analysis is
A certificate of analysis (COA) is a signed document issued by an analytical laboratory that records the identity and purity of a specific batch, or lot, of material. It is tied to a lot number, not to a product line in general, so two vials of the same peptide from different batches each have their own certificate. A COA answers two questions that matter most in research: is this the correct molecule, and how much of the sample is that molecule versus everything else.
One certificate per lot
Because purity and identity are measured on the finished batch, a COA is only meaningful for the lot it was run on. Always match the lot number on your vial to the lot number on the certificate.
What we test for
A peptide COA is built from a small number of complementary analytical methods. Each one answers a different question, and read together they describe the batch.
Identity (mass spectrometry)
Mass spectrometry (MS) measures the molecular weight of the peptide and confirms it matches the expected mass for the sequence, proving the correct molecule was made.
Purity (HPLC)
High-performance liquid chromatography (HPLC) separates the sample into its components and reports the main peak as a percentage, the purity figure, typically stated as a target of 98% or higher.
Water & salt content
Methods such as Karl Fischer titration and acetate testing report residual water and counter-ion content, which is why the net peptide mass can differ from the gross vial weight.
Appearance & lot data
The certificate also records appearance, batch and lot numbers, manufacture and retest dates, and the storage conditions the figures are valid under.
How HPLC and mass spectrometry read a batch
The two headline tests work together. HPLC pushes the dissolved sample through a column so that the target peptide and any impurities travel at different speeds and come off at different times; a detector plots those as peaks, and the area of the main peak divided by the total area gives the purity percentage. Mass spectrometry then ionises the sample and measures the mass-to-charge ratio of the fragments, so the observed molecular weight can be compared against the theoretical weight for the sequence. A batch that shows a single dominant HPLC peak and the correct mass is both pure and correctly identified.
How our COA testing works
Peptide.ST does not manufacture in a vacuum. Our compounds are produced and tested by our partner laboratory in Poland, and every batch is documented before it is released.
Synthesis and in-house testing
The Poland laboratory synthesises the peptide and runs its own HPLC and mass-spectrometry analysis on the finished lot, issuing a first-party certificate of analysis for that batch.
Independent third-party verification
The same batch is verified by an independent third-party laboratory, so the identity and purity figures do not rest on a single source. This is the check that turns a supplier claim into an independently confirmed result.
Lot traceability
Each vial is tied to its lot number, and that lot maps back to both certificates, so any vial you receive can be traced to the exact test data it was released against.
Batch lookup
The certificate for your batch is made available to you, so you never have to take purity on trust. Look it up with the code on your vial.
First-party and third-party COAs
The difference between the two matters, and we provide both.
| Certificate | Who issues it | What it gives you |
|---|---|---|
| First-party | Our partner laboratory in Poland | The manufacturer's own HPLC and MS analysis of the exact batch that was made. |
| Third-party | An independent laboratory | A separate, unaffiliated re-test of the same batch, so purity and identity are confirmed by a second source. |
Both certificates come from the Poland laboratory relationship and travel with the lot. Having a first-party and an independent third-party result on the same batch is what lets a researcher rely on the numbers rather than on a brand's word.
How to read your COA
- Lot / batch number: confirm it matches the number printed on your vial.
- Purity (HPLC): the main-peak percentage, usually a target of 98% or higher.
- Molecular weight (MS): the observed mass should match the theoretical mass for the sequence. See the peptides reference list for expected weights.
- Dates and storage: the manufacture or retest date and the storage conditions the result is valid under. See our storage guide.
Look up your batch
Every batch we ship carries a lookup code. Enter it on our certificate lookup page to pull the certificate of analysis for that exact lot.