Lab Quality & Testing
How to Read a Peptide COA: A Complete Walkthrough
A certificate of analysis is only useful if you can interrogate it. Here is what each section should contain and which omissions should stop an order.
August 25, 2026 · 8 min read · Novanta Research
The header: identity and lot
The top of a certificate should state the compound name, the sequence or at minimum the molecular formula, the theoretical molecular weight, the lot number, the date of analysis and the testing laboratory. If the lot number on the document does not match the label on the vial in your hand, the document tells you nothing about that vial.
A certificate with no lot number is a marketing sheet, not a certificate.
The purity section
Purity is normally reported as area percent from a reverse-phase HPLC run at a stated wavelength, usually 214 or 220 nanometres. You should be able to see the chromatogram itself, not just a number: the main peak, the retention time, and the baseline.
Look at the impurity peaks. A single 99.2% figure sitting above a chromatogram with a large shoulder on the main peak means something different from the same figure above a flat baseline.
The identity section
Mass spectrometry confirms that the purified material is the right molecule. The reported observed mass should match the theoretical mass within the instrument's stated tolerance, and the spectrum should be shown.
Purity without identity is meaningless — a lot can be 99% pure and 100% the wrong compound.
Net peptide content and residuals
Net peptide content, usually determined by nitrogen analysis or amino acid analysis, states how much of the vial mass is peptide rather than counter-ion salt and residual water. It is typically well below 100% and is essential for accurate concentration calculations.
Well-documented lots also report water content and residual solvent, and where relevant endotoxin and sterility results.
- Compound name, sequence and theoretical mass
- Matching lot number and analysis date
- HPLC chromatogram with purity as area percent
- Mass spectrum with observed versus theoretical mass
- Net peptide content
- Testing laboratory identified by name
Red flags
Treat these as disqualifying: no lot number, no chromatogram image, an anonymous testing laboratory, an analysis date that predates the manufacturing date, or a document reused across multiple lots with only the header changed.
Novanta publishes third-party HPLC and mass spectrometry documentation per lot on the certifications page, and every lot is released at 99%+ purity.
Frequently asked
- Why is net peptide content lower than purity?
- They measure different things. Purity is the share of peptide material that is the correct sequence; net peptide content is the share of total vial mass that is peptide at all, with the remainder being counter-ions such as trifluoroacetate plus residual water.
- Should the COA come from a third party?
- Yes. In-house data can be accurate, but independent testing removes the conflict of interest and is the standard we hold every Novanta lot to.
Keep reading
For laboratory and research use only. Not for human or veterinary consumption. Novanta Research is not a compounding pharmacy and nothing in this article is medical advice or a claim that any compound diagnoses, treats, cures or prevents any condition.