Understanding and reading a Certificate of Analysis (COA)

For research peptides, the COA is the most important document of trust. Here, we explain field by field what it contains – and how to distinguish a genuine certificate from a worthless one.

What is a COA?

One Certificate of Analysis English Certificate of Analysis, kurz COA) dokumentiert die Ergebnisse der Qualitätsprüfung einer konkreten Production batch. It is not a general marketing document but batch-specific: every batch (lot) has its own COA with its own number. A COA is only meaningful when it has been issued by an independent third-party laboratory was created – not by the seller themselves.

The key fields at a glance

• Product / Identity Peptide name, sequence if applicable, CAS number, and molecular formula.
• Batch number Unique identifier of the tested batch.
• Purity (HPLC): Percentage purity, typically stated as "≥ 99%", determined by high-performance liquid chromatography.
• Identity / Molecular Mass (LC-MS): Confirmation that the measured mass corresponds to the expected molecular mass.
• Appearance e.g. „white lyophilised powder“ – a simple visual plausibility check.
• Test Date & Method When and by which procedures it was tested.
• Labour / Signature: Name of the testing laboratory or responsible person.

HPLC and LC-MS – a brief explanation

The two central values stem from two procedures: HPLC mostly misses the Purity (what percentage of the sample is the target molecule), LC-MS confirms the Identity about the molecular mass. Together, they answer the two most important questions: „Is it the right molecule?“ and „How pure is it?“ A detailed explanation can be found in the article Peptide Purity: HPLC and LC-MS Explained.

How to recognise a trustworthy COA

• Third-party lab The certificate comes from an independent laboratory, not from the seller's own production.
• Mentioned methods: HPLC and LC-MS are named explicitly – including the purity value and the measured mass.
• Readable & complete: No cropped image, no generic template without a batch number.

Warning signs no COA at all; a „COA“ without a batch number; a document that is identical for all products; or a certificate that originates solely from the seller and does not specify a method.

This is how BlitzLab handles COAs

At BlitzLab, each batch is externally tested using HPLC and LC-MS; the batch-specific COA can be viewed on the respective product page. More about our quality and compliance framework can be found on the page Compliance / RUO.