How to Read a Peptide Certificate of Analysis (COA)
High Point Research Peptides · 2026-09-03
What a COA is
A certificate of analysis is a document issued for a specific production lot of a compound, reporting the results of analytical testing performed on that lot. For research peptides, a meaningful COA answers two questions: does the material have the correct molecular identity, and what percentage of the sample is the target peptide?
A COA applies to one lot — not to the product in general, and not to every vial a supplier has ever sold. Always confirm the lot number on the COA matches the lot number recorded for the material you received.
Purity by HPLC
High-performance liquid chromatography separates the components of a sample as they pass through a column, producing a chromatogram with a peak for each component. The area of the main peak as a percentage of total peak area is the reported purity. A research-grade peptide is typically expected to be 98% or higher, with the chromatogram showing a single dominant peak.
When reviewing the HPLC section of a COA, check the reported purity percentage, the detection wavelength, and whether the underlying chromatogram is shown. A purity number with no chromatogram is difficult to verify independently.
Identity by mass spectrometry
Mass spectrometry (MS) measures the mass-to-charge ratio of the molecules in a sample. For a peptide, the observed molecular weight should match the theoretical molecular weight of the intended sequence. This confirms the vial contains the compound on the label rather than a different or truncated sequence.
A complete COA reports both the theoretical and observed masses. Agreement between them — typically within a fraction of a Dalton depending on the instrument — is the identity check.
What else to look for
Testing laboratory: credible COAs come from an identified analytical laboratory, ideally independent of the supplier. Date: the test date should be consistent with the lot's production timeline. Lot traceability: the supplier should record which lot each order was fulfilled from, so documentation can always be traced back.
High Point Research Peptides publishes third-party HPLC and MS reports per lot and records lot numbers against every order. Verified account holders can browse current reports on the lab results page.
Research use only. The compounds referenced in this guide are not drugs, foods, supplements, or cosmetics, and are not intended for human or veterinary use. This article is educational and is not medical advice.
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