How to Read a Certificate of Analysis

A Certificate of Analysis (COA) is a controlled document that records the analytical results a laboratory obtained for a specific batch of material. It is a record of what was measured for a particular lot — not a general statement about a product line. Two batches of the same catalogue item will each have their own COA.

Because a COA is lot-specific, the first task when reading one is to confirm that the identifiers on the document match the material in front of you.

The header of a COA carries the identifiers that bind the document to a physical lot. Reconcile each of these against your inventory record and the container label before relying on the analytical results below them.

• Catalogue / product number — the item identifier.
• Batch number and lot number — the specific production and inventory units the results describe.
• Certificate identifier and version — a COA can be superseded; always read the current version.
• Report, testing, and sample-received dates — establish when the analysis was performed.
• Reviewer and approval date — indicate the document was reviewed before release.

The analytical section reports identity and purity determinations. Identity answers "is this the compound it claims to be"; purity answers "what proportion of the material is the target compound". Each result should name the method used to obtain it so the number can be interpreted in context.

Where a determination was not performed for a given batch, a well-formed COA states that explicitly rather than leaving the field blank. Treat an absent result as "not determined", not as a passing result.

• Appearance — a descriptive observation of the physical form.
• Identity — commonly by mass spectrometry (for example LC-MS) confirming the expected mass.
• Purity — commonly by HPLC, reported as an area-percent against a defined method.
• Additional determinations — water content, residual solvent, or endotoxin, when applicable to the material.

A COA is only meaningful when it is matched to the lot it describes. In a lot-controlled workflow, the document, the inventory record, and the container label all carry the same batch and lot numbers, and a verification lookup resolves the document from any of those identifiers.

If the numbers do not agree, stop and resolve the discrepancy through your supplier before use. A mismatch means the document and the material have not been shown to correspond.