What Should a Research Peptide COA Include?
A certificate of analysis (COA) is the single most important document a research peptide supplier can hand you. If a COA is missing key sections, or if the numbers don't match the lot number on your vial, the material behind it is not verifiable. This guide breaks down what a defensible peptide COA contains.
Batch identity and lot number
The COA should reference the exact lot number printed on your vial, plus manufacture date, expiry, and quantity. "Typical" or "representative" COAs are not batch-specific and don't count.
Purity — HPLC-UV chromatogram
HPLC purity should be documented as a percentage (≥99%) with the chromatogram attached or available on request. Column, gradient and detection wavelength should be listed. Impurity peaks above the reporting threshold should be identified where possible.
Identity — LC-MS or MALDI-TOF
Mass spectrometry confirms the peptide is what the label says it is. The COA should show observed mass vs theoretical mass with an acceptable tolerance.
Net peptide content
Because lyophilized peptide contains counter-ion and residual water, actual peptide content by mass is typically 70–90% of gross vial fill. Net peptide content by Kjeldahl or elemental analysis is critical for dosing accuracy in research.
Endotoxin (LAL)
For any peptide intended for cell culture or in-vivo research use, endotoxin should be measured by LAL and reported in EU/mg. PX1 publishes endotoxin reports for every batch.
Appearance, closure and storage
Physical description of the lyophilized cake, stopper/seal integrity, and recommended storage temperature all belong on a complete COA.
Frequently Asked Questions
What should a peptide COA include?
Batch lot number, HPLC purity, mass-spec identity, net peptide content, endotoxin (LAL), appearance and storage. All tied to the specific lot shipped.
Is a 'typical' COA acceptable?
No. A COA must reference the exact lot number on your vial — a generic template does not verify the material in your hand.
Related pages
All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.