Research-use information only. The peptides discussed are laboratory reference materials, not for human or animal consumption.
A Certificate of Analysis (COA) is the single most important document in research-peptide sourcing. It is the third-party lab report that proves what is actually in the vial. If a supplier cannot produce one tied to your specific batch, there is no way to verify identity or purity — and no reason to buy. Here is how to read one.
The two tests that matter
HPLC — purity
High-Performance Liquid Chromatography separates the contents of the sample and reports each component as a percentage. The headline number is purity. For research peptides you want ≥98%. The chromatogram should show one dominant peak; large secondary peaks indicate impurities or degradation.
Mass Spectrometry (MS) — identity
HPLC tells you how pure the sample is, but not what it is. Mass spectrometry measures the molecular weight and confirms it matches the known weight of the target peptide. A high purity number is meaningless if the MS shows the wrong molecule — you would simply have a very pure wrong compound.
The checks that catch fakes
- Batch number matches your vial. A COA for batch A proves nothing about the vial you received from batch B. Generic or batch-less COAs are a red flag.
- An independent lab issued it. An in-house COA from the seller is weaker evidence than a third-party report.
- The peptide name and molecular weight are stated and match the published values for that peptide.
- A recent date. Identity does not change, but a current report shows the batch was actually tested.
Quick reference
- Purity (HPLC): want ≥98%, single dominant peak.
- Identity (MS): measured mass matches the peptide’s known molecular weight.
- Batch: COA batch number = the number on your vial.
- Source: independent third-party lab, recent date.
Anything vague, missing, or unwilling to be shared = walk away.
How we handle COAs
Every batch we stock is independently tested by HPLC and MS, and the COA is sent on request, tied to the batch number on your vial. You can request a COA before ordering, and browse the catalogue to see what is in stock.