In this guide
What a COA is
A Certificate of Analysis (COA) is a lab report that documents what's actually inside a vial. For research peptides, a credible COA answers two questions: Is this the right compound? (identity) and How pure is it? (purity). The two analytical methods that answer these are HPLC and mass spectrometry.
HPLC: verifying purity
High-Performance Liquid Chromatography (HPLC) separates the contents of a sample into its individual components and measures how much of each is present. On the resulting chromatogram, the target peptide shows up as a dominant peak. The size of that peak relative to everything else gives the purity percentage — for example, "≥99% by HPLC" means the target compound accounts for at least 99% of the sample, with impurities making up the rest.
Mass spectrometry: verifying identity
Mass spectrometry (MS) measures the molecular weight of the compound. Every peptide has a known, expected mass based on its amino-acid sequence. If the measured mass matches the expected mass, that confirms the vial actually contains the peptide it claims to — not a cheaper substitute or a mislabeled compound. HPLC tells you how pure; MS tells you what it is. You want both.
How to read a COA
- Product & batch/lot number — should match the label on your vial.
- Purity (HPLC) — look for a clear percentage, ideally ≥98–99%.
- Identity (MS) — observed mass should match theoretical mass.
- Testing date and lab — a credible COA names an independent lab, not just the seller.
Why third-party testing matters
A seller testing its own product has an obvious conflict of interest. Independent, third-party testing removes that conflict — an outside lab with no stake in the outcome verifies the result. At Patriot Labs, every batch is sent to an independent US laboratory for HPLC and mass-spec analysis, and the COA is tied to the batch code on each vial. You can read more about our standards on the about page.
Want the COA for a specific batch? Email us your product and lot number and we'll send the full third-party report.
Request a COAFor in-vitro research and laboratory use only. Not for human consumption.