In peptide research, a result is only as trustworthy as the material behind it. A Certificate of Analysis (COA) is the document that tells you what a vial actually contains — its identity and its purity — verified by independent testing. Understanding how to read one is a core skill for any researcher.
What a COA is
A COA is a batch-specific report from an analytical laboratory. Because it is tied to a specific production batch, it reflects the exact material you receive rather than a generic specification. At GenoPept, every product ships cross-referenced to its own Certificate of Analysis.
The key sections
Identity (Mass Spectrometry)
Mass spectrometry (MS) confirms that the molecule present has the expected molecular weight — in other words, that the vial contains the peptide it is labelled as, not a different or truncated sequence. The observed mass should match the theoretical mass for that peptide.
Purity (HPLC)
High-Performance Liquid Chromatography (HPLC) separates the sample into its components and measures how much of the total is the target peptide versus impurities. Purity is reported as a percentage; research-grade material is typically ≥ 98–99%. On the chromatogram, a single dominant peak indicates a clean product, while multiple significant peaks indicate impurities or degradation.
How to read the numbers
- Purity % — higher is better; look for ≥ 99% where possible.
- Observed vs theoretical mass — these should match closely.
- Batch/lot number — should correspond to the vial in your hand.
- Test date — confirms the analysis is current for that batch.
Why it matters
Without a COA, purity and identity are just claims. Impurities can confound assays, and a mislabelled or degraded peptide can invalidate an entire experiment. A verifiable COA lets you attribute your results to the compound you intended to study — and makes your own work reproducible for others.
The GenoPept standard
GenoPept’s approach is analytical purity over presentation: every batch is independently HPLC- and MS-verified to ≥ 99% purity, with the COA provided as standard rather than on request. You can review the range in the research peptide store or read more on the COA Certificates page.
Related guides
Research use only. GenoPept products are supplied strictly for in-vitro laboratory and scientific research and are not for human or veterinary use.