Reading a Certificate of Analysis

A Certificate of Analysis (COA) is a lab's signed statement describing what a specific batch of material is and how pure it is. For research materials, the COA is the single most useful document a buyer can read — but only if you know what each section means and what it leaves out.

What a COA can and cannot tell you

A COA reports measurements made on one batch. It is not a guarantee about future batches, and it is not a safety endorsement. A strong COA tells you the identity of the material, its measured purity, and the analytical methods used to reach those numbers. A weak COA shows a number with no method, no batch ID, and no lab attribution.

The sections that matter

• Identity confirmation. Mass spectrometry (MS) or another orthogonal method should confirm the molecule is what the label claims. A purity number is meaningless if identity was never established.
• Purity by HPLC. High-performance liquid chromatography separates the target from impurities. Look for the actual chromatogram, not just a quoted percentage.
• Batch / lot number. The COA should reference a specific lot that matches the physical product.
• Lab attribution. An independent, accredited lab (for example, ISO/IEC 17025 scope) carries more weight than an unnamed "in-house" result.
• Date and signatory. Recent, signed, and traceable to a person or lab.

Red flags

• A purity percentage with no chromatogram and no method.
• No batch number, or a batch number that does not match the product.
• Identity "confirmed" by appearance or solubility rather than MS.
• A COA that is reused across visibly different products.

A COA is evidence, not marketing. When a vendor publishes complete, per-batch documentation from an independent lab, you can evaluate their claims yourself — which is exactly what our vetting methodology rewards.