How to Read a Certificate of Analysis (COA)
A field-by-field walkthrough of a research-peptide Certificate of Analysis and what each entry tells you.
Header — who issued it
Reputable COAs are issued by an independent third-party laboratory, with the lab's name, address, and an accreditation reference where applicable. A COA generated by the supplier itself is not equivalent.
Sample identification
The compound name, lot/batch number, and analysis date should be unambiguous. The lot number on the COA should match the lot number on the supplier's listing and on physical packaging.
Methods and results
- HPLC purity — chromatogram and a numeric purity value.
- Mass spectrometry — theoretical and measured mass.
- Appearance / colour — e.g., "white lyophilised powder".
- Net peptide content — sometimes reported separately from purity.
Storage and stability statement
Most COAs end with a recommended storage condition (typical: store cold, protected from light). This statement is generic; suppliers may provide additional handling notes elsewhere.