How to read a peptide Certificate of Analysis

A Certificate of Analysis (CoA) is a document issued by a testing laboratory that reports the quality, purity, and identity of a specific batch of compound — the primary evidence to compare when evaluating peptide suppliers side by side.

CoA pass thresholds at a glance

Using a CoA to compare suppliers

When comparing suppliers, the CoA is the one document that lets you check a claim rather than take it on trust: batch number (does it match what you are ordering), HPLC purity, mass-spectrometry identity, and the testing lab’s independence from the seller. A supplier that cannot produce a current, batch-matched CoA is not comparable on the criteria that matter.

Frequently asked questions

What is the difference between HPLC purity and mass spectrometry identity confirmation?

HPLC (High-Performance Liquid Chromatography) purity is peak-area normalisation — the canonical purity metric on a CoA, reported as a percentage. Mass spectrometry confirms identity: the observed molecular mass should match the theoretical mass within about ±1 Da. Purity tells you how clean the batch is; mass spec tells you it is actually the compound claimed.

Related research

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