Guide
How to read a Certificate of Analysis
A field guide to interpreting the COA shipped with every batch — identity, purity, residual solvents, and what each test method confirms.
What a COA covers
A Certificate of Analysis (COA) documents the identity and purity of a specific manufacturing lot. Each lot should have its own COA, not a generic certificate for the product family.
Identity tests
Mass spectrometry (typically ESI-MS or MALDI-TOF) confirms the molecular weight matches the expected mass for the peptide sequence. Amino acid analysis confirms composition.
Purity tests
Reverse-phase HPLC reports the percentage of the target peptide relative to other UV-absorbing impurities. Typical specifications for research-grade peptides are ≥95% or ≥98% area purity.
What to look for
Verify the lot number on the COA matches the vial label. Confirm the test date, the testing lab, and that the reported purity meets the product specification.